Everyone I know compares their $2000 macbook pro to a $400 Dell PC and blames it on the operating system. If you had exactly the same hardware in both systems I highly doubt you'd be able to tell.
Seriously, you can say that you can't run Photoshop, Dreamweaver and Final Cut Pro at the same time... you definitely are comparing your mac to a single-core PC.
You can build your own, upgrade one you purchased, or choose from hundreds of distributors each with different offers and setups. With Mac's, you have a general build that you can change out a few pieces of. And some distributors do have pricey computers. If you're going to spend $1200 without looking at the specs, why are you buying a computer?!
I just built my friend a computer for $1050 just last month and heres the specs, if this means nothing to you then don't compare performance between PC and Mac:
GFX: EVGA 8800GT Superclocked 512mb
CPU: Core 2 Duo E6750 Conroe (2.66ghz)
RAM: 2x2gb DDR2 800mhz
HDD: 500gb Seagate 7200rpm
included case and 18" LCD monitor (Not OS, he had a copy)
I'm sorry, you won't find anything like that for your precious MacBook Pro. I also bought a 20.1" LCD flat panel in November for $210, compared to
this?.
And yeah, its hard to compare desktop prices to notebook prices. But its still the same scenario.
And basically
everything made available for a computer is available on Windows, with the exception of a very few apple-exclusive programs/software. Unlike with Microsoft, Apple is compelled to make their operating system work with Windows.
Linux is mainly for programmers and network administrators, or the adventurous power user.