I wouldn't spend that kind of money on that computer. No matter what you do, it will never play Crysis decently. You have a single core AMD processor that only runs at 2.2 Ghz's, The minimum required is a 2.8 for XP and a 3.2 for Vista. Cryisis Specs
To be honest, your computer is not really worth the cost of the parts you are looking to put in it. You can get a low end Dell
Duo core machine for $399. You could build a much better one for the same price if you built it yourself. The fact that you are willing to swap out power supplies and GPU's means you CAN build your own.
If you can't afford to build or buy a computer with at least a duo core processor, you REALLY can't afford to throw what money you have at an obsolete computer.
I used Dell as a reference point just because I had to use someone lol. You can find something similar on Compaq's site I'm sure.
EDIT: I hit reply to soon: If you don't have the money right now for a new system, you would do better just gritting your teeth and dealing with what you have until you can save up some more cash to get a new system rather than spending another dime on the one you have. I know it sucks, I've been in that position, but it is what it is. They went from those 2.x GB single core processors up to 3.8 almost over night and then they went to the Duo cores without even catching their breaths. I got a 3.2 Pentium4 and within 2 years it was barely at the minimum specs to play games. If your computer is at the mins, don't even buy the game. It will "play" it, but not in a way anyone would want to play.
EDIT II: If you go to the computer building and upgrade
thread and ask about building a budget gaming rig good enough to play Cryis, DJBPACE07 will give you some great advise. He really knows his hardware and keeps current on the prices. He will shoqw you how to get the best performance for the least amount of money. Building a computer is really no harder than switching out a video card and GPU, you CAN do it.
Edited by DeathStalker, 24 April 2010 - 08:17 AM.