Sorry if I'm posting this in the wrong place. I usually do.

The problem is simple enough. I can't really figure out why my site looks awful in IE 6 and MSIE 5 and lower. I'm thinking it's CSS, but that's about it.
Please have a look and advise.

http://www.hostreactor.net

You're getting Float drop - because of IE's broken box model.

My suggestion would be to narrow the main and right columns so that they take up no more than 96% of the 760px width and the dropping should stop.

Found it.

You have a
padding:0 20px 20px;
on the div #ja-content.

It pushes the border of your div #ja-mainbody-fl a bit too far, and the float makes that the right bar goes below the lower right corner of this first div.

remove the padding, or put it in a ie specific description to avoid it.

<!--[ if lte IE 6 ]>
#ja-content{
 padding:0px!important;
}
<![endif]-->

thanks for the replies!
I made the required modifications but I'll have to wait and see if they work - as I have upgraded to IE 7 a month ago
another problem is that some of the writing shows in white. This happens in google's cache too. Have a look:
google's cache

I have not tried this modification in ie7, as I don't have it.
Maybe you will need to alter the code to include IE7.

As for the white text, I have no idea.....
Try to put it in a span, and to apply a class or the color as a style on your text.
That should solve it, but I don't see what is causing this.

BTW, you should take some time to clean up your code.
It's a real mess...
My validator throws me that:

Result: 55 errors / 11 warnings

line 1 - Error: no document type declaration; will parse without validation
line 2 column 66 - Error: an attribute value must be a literal unless it contains only name characters
line 2 column 100 - Error: an attribute value must be a literal unless it contains only name characters
line 2 column 146 - Error: an attribute value must be a literal unless it contains only name characters
line 2 column 154 - Error: an attribute value must be a literal unless it contains only name characters
line 2 column 227 - Error: an attribute value must be a literal unless it contains only name characters
line 2 column 256 - Error: an attribute value must be a literal unless it contains only name characters
line 2 column 285 - Error: an attribute value must be a literal unless it contains only name characters
line 2 column 314 - Error: an attribute value must be a literal unless it contains only name characters
line 2 column 343 - Error: an attribute value must be a literal unless it contains only name characters
line 2 column 372 - Error: an attribute value must be a literal unless it contains only name characters
line 3 column 15 - Error: an attribute value must be a literal unless it contains only name characters
line 3 column 44 - Error: an attribute value must be a literal unless it contains only name characters
line 3 column 73 - Error: an attribute value must be a literal unless it contains only name characters
line 3 column 102 - Error: an attribute value must be a literal unless it contains only name characters
line 3 column 131 - Error: an attribute value must be a literal unless it contains only name characters
line 3 column 160 - Error: an attribute value must be a literal unless it contains only name characters
line 5 column 154 - Warning: cannot generate system identifier for general entity "hl"
line 5 column 154 - Error: general entity "hl" not defined and no default entity
line 5 column 156 - Error: reference to entity "hl" for which no system identifier could be generated
line 5 column 153 - Info: entity was defined here
line 5 column 160 - Warning: cannot generate system identifier for general entity "client"
line 5 column 160 - Error: general entity "client" not defined and no default entity
line 5 column 166 - Error: reference to entity "client" for which no system identifier could be generated
line 5 column 159 - Info: entity was defined here
line 5 column 177 - Warning: cannot generate system identifier for general entity "rls"
line 5 column 177 - Error: general entity "rls" not defined and no default entity
line 5 column 180 - Error: reference to entity "rls" for which no system identifier could be generated
line 5 column 176 - Info: entity was defined here
line 5 column 208 - Warning: cannot generate system identifier for general entity "sa"
line 5 column 208 - Error: general entity "sa" not defined and no default entity
line 5 column 210 - Error: reference to entity "sa" for which no system identifier could be generated
line 5 column 207 - Info: entity was defined here
line 5 column 213 - Warning: cannot generate system identifier for general entity "strip"
line 5 column 213 - Error: general entity "strip" not defined and no default entity
line 5 column 218 - Error: reference to entity "strip" for which no system identifier could be generated
line 5 column 212 - Info: entity was defined here
line 5 column 369 - Warning: cannot generate system identifier for general entity "amp"
line 5 column 369 - Error: general entity "amp" not defined and no default entity
line 5 column 372 - Error: reference to entity "amp" for which no system identifier could be generated
line 5 column 368 - Info: entity was defined here
line 5 column 393 - Error: reference to entity "amp" for which no system identifier could be generated
line 5 column 368 - Info: entity was defined here
line 5 column 432 - Error: reference to entity "amp" for which no system identifier could be generated
line 5 column 368 - Info: entity was defined here
line 5 column 443 - Error: reference to entity "amp" for which no system identifier could be generated
line 5 column 368 - Info: entity was defined here
line 5 column 477 - Error: reference to entity "amp" for which no system identifier could be generated
line 5 column 368 - Info: entity was defined here
line 5 column 497 - Error: reference to entity "amp" for which no system identifier could be generated
line 5 column 368 - Info: entity was defined here
line 8 column 2 - Error: "DOCTYPE" declaration not allowed in instance
line 16 column 166 - Error: reference to entity "amp" for which no system identifier could be generated
line 5 column 368 - Info: entity was defined here
line 16 column 182 - Error: reference to entity "amp" for which no system identifier could be generated
line 5 column 368 - Info: entity was defined here
line 160 column 35 - Warning: cannot generate system identifier for general entity "nbsp"
line 160 column 35 - Error: general entity "nbsp" not defined and no default entity
line 160 column 39 - Error: reference to entity "nbsp" for which no system identifier could be generated
line 160 column 34 - Info: entity was defined here
line 186 column 39 - Error: reference to entity "nbsp" for which no system identifier could be generated
line 160 column 34 - Info: entity was defined here
line 197 column 39 - Error: reference to entity "nbsp" for which no system identifier could be generated
line 160 column 34 - Info: entity was defined here
line 224 column 78 - Warning: cannot generate system identifier for general entity "x"
line 224 column 78 - Error: general entity "x" not defined and no default entity
line 224 column 79 - Error: reference to entity "x" for which no system identifier could be generated
line 224 column 77 - Info: entity was defined here
line 224 column 82 - Warning: cannot generate system identifier for general entity "deptid"
line 224 column 82 - Error: general entity "deptid" not defined and no default entity
line 224 column 88 - Error: reference to entity "deptid" for which no system identifier could be generated
line 224 column 81 - Info: entity was defined here
line 224 column 170 - Error: reference to entity "x" for which no system identifier could be generated
line 224 column 77 - Info: entity was defined here
line 224 column 179 - Error: reference to entity "deptid" for which no system identifier could be generated
line 224 column 81 - Info: entity was defined here
line 224 column 182 - Warning: cannot generate system identifier for general entity "refer"
line 224 column 182 - Error: general entity "refer" not defined and no default entity
line 224 column 187 - Error: reference to entity "refer" for which no system identifier could be generated
line 224 column 181 - Info: entity was defined here
line 249 column 11 - Warning: cannot generate system identifier for general entity "copy"
line 249 column 11 - Error: general entity "copy" not defined and no default entity
line 249 column 15 - Error: reference to entity "copy" for which no system identifier could be generated
line 249 column 10 - Info: entity was defined here
line 252 column 62 - Error: reference to entity "amp" for which no system identifier could be generated
line 5 column 368 - Info: entity was defined here
line 252 column 78 - Error: reference to entity "amp" for which no system identifier could be generated
line 5 column 368 - Info: entity was defined here
line 270 column 5 - Error: end tag for element "DIV" which is not open
line 271 column 5 - Error: end tag for element "DIV" which is not open

It's the output of this firefox extention:
http://users.skynet.be/mgueury/mozilla/


And get firebug (http://www.getfirebug.com) to inspect your css.
he can show you which part of which css rule is applied to the element you are hovering. And you can even change them and preview in the browser the changes: