Buy illegal version SP2, and just update it
(just a suggestion, never try it :P)

I've been playing the crysis beta. It's not even that good. The graphics are great but team fortress 2 is a way better (multiplayer) shooter. I'm hoping (and willing to bet) that Crysis's single player will be pretty good, but the multiplayer has been pretty generic thus far.

 I had to install an illegal version of windows xp on my friends PC cause he bought a Sony pc, and they dont ship windows cds with them.  He called them and asked them to ship it to him, they said they couldn't cause they don't carry xp anymore, just vista, so they told him to ship his computer and they would install it for him for 250 dollars.  So i was like, F*** that dude, i'll just obtain a version that will work for you.

There's a crack you can put on it that makes windows think its genuine.  I can't tell you where to get it. sorry. 

 i don't wanna play it for the multiplayer either, just for the best graphics ever shown to mankind

Why don't you backup all your files on DVDs? As everyone said up there, the best way to go is a fresh install of either Vista or SP2 then upgrade.

Also, you can play Crysis on XP I think...

 i liked the multiplayer, it's the perfect game when i feel like sniping.

 He wants DX10,

My suggestion is to learn how to properly partition your drive with PartitionMagic and then learn how to set up a Vista/XP dual boot.  If you don't have the hard drive space for that...then delete some stuff =P

I actually just went through this recently, only instead of partitioning my drive I ordered another 320GB drive =P Gonna have to re-install vista once it gets here but no big deal. 

Dont give yourself excuse, buy a genuine one 

I was using a pirated XP sp1, without the bug fixing of SP2, my PC was attacked by different kinds of virus, malware, spyware. Then I searched around the net, tried various hack program  to install SP2 without the key validation. I messed up my computer finally and found that it's not worth to spend so many time and effort on it

 Now i'm using a genuine Vista Home, i feel good.

What you want is SP2 redist... sometimes referred to as SP2 for IT professionals... basicall instead of installing it from some crappy online validation program you just download the package to your computer.

No issue with validation. Last I checked you could get sp2 redist from a number of places. I downloaded mine from the normal MS page... That is the best way to get SP2, cuz then you can back that up on a cd... or use nLight to make a custom install disk which includes the sp2 pack.

But I'm not saying I used it with an unvalidated copy of windows... I just know if you have the redist it doesn't check validation.

Eh, I don't care to help pirates.

Not saying all my versions of XP are legitimate either...but if you're going to steal, you better get it right yourself, in my opinion.

EDIT:  My main problem with most pirates is that they have some grand goal to not allow Microsoft and big corporations to "broaden their monopolies."  That's all BS in my opinion.  You do it because you don't want to pay that much for an OS, just like many others.