Will a ATI RADEON 9600 PRO run Cysis or any modren game?

Sorry, that was rude.

No, unfortunately, it most definitely will not. It might be able to handle games from 5 years ago... sorry.

It could if you could boot into Windows, on very low settings. Of course sense its PPC, you can't do that.

So no, unless they make a Mac version, and even if they did it would be Intel only.

World of Warcraft should run nicely on it.

Not at frame rates you'd want to play. You can't use boot camp because you have a PowerPC chip, not an Intel. No Crysis. The graphics are nice but the game play is pretty bland, you're not missing anything. You may want to build a cheap PC (What you can do with $500 is amazing these days), or you also might be better served by getting a new computer. I use a Quicksilver too and it's getting retired to my dad's suburb office to make room for a Mac Pro in January or February.

I would sit on your money and get a new computer instead of purchasing upgrades for an 7 year old machine. Speaking of which, the Quicksilver line is officially 7 years old as of July 18, 2008.