Which domain name extension should I use?

I am designing a new web page with news, forum, chat, gallery etc. This is for the British and MAYBE in the future I will expand the website to include USA, Poland, Germany, Holland and some other countries.

I have checked the Domain Name and it is available with .com, .net and .co.uk (this is used in UK) and other endings are also available.
Which extension should I use? Here, I am a bit worried about the search engine indexing.

Thanks

If you're planning to aim for an international audience I would opt for a .com

If you have to choose only one, go with .com as it's the best known so people will automatically try typing that first. I would recommend you buy all three and just redirect the second two towards the .com website. Then you don't have to worry about anyone hijacking your traffic so easily if you become very popular.

Any reason why you can't use both? Domains aren't exactly expensive. You could buy both and then use your preferred domain and point the other one to it.

If your main target is the United Kingdom then really *.co.uk is the primary choice. cc-TLDs tend to rank better in geographical results; however if you did go with the *.com you could set geo-targeting in Google Webmasters Central. I personally with my experience would go with the *.co.uk extension.

If your business is for UK only - go with CO.UK. If you are looking to be present around the World I think that .COM will be the best solution for you.

.com is more preferable.

.com is easy to remember..........

International = .com if you are selling a product / service then I recommend .co.uk as this makes people from the UK trust the site a bit more, all of my sites are .co.uk bar one which is .net (Couldnt get the .co.uk)

.com would be better for you

Use .com extension if you plan to have worldwide audience.

Go with .COM!
You will lose absolutely nothing

If you can afford that - go with both of them. I think that soon you will understand that you have made right step.

I would definately choose the .co.uk if you're aiming at a UK audience. But I would also definately buy the .com and save that if you decide to go international.

I think UK people just prefer .co.uk sites, it looks friendly in the serps

I think .com is the way to go for the primary design. I would recommend buying 2 or 3 other matching domains with different tlds anyway. Just to protect your name, and you never know you might need them.

I would get both but only use .co.uk as real page since it is a British site. I would forward the .com to the .co.uk I believe using a 301 direct (someone correct me if i'm wrong).