is it worth it to buy a geforce 6600GT 128MB PCI-E for a friend's gaming computer? How will games like Oblivion and Prey work? What about half life 2 and Doom 3? Battlefield 2? P4 D - 2.66GHz 1024MB DDR2 RAM ASUS A8N-SLI Motherboard Gigabyte Nvidia Geforce 6800 Ultra 256MB PCI-E Creative SoundBlaster Audigy 2 ZS Platinum 2x Western Digital Raptor 74GB

What are the specs to this "gaming computer"? The Radeon X1600Pro is usually a lot cheaper than a 6600GT

Depends on what you're paying. It's a good card but stock fan is so loud you better have a good sound system. Plays Prey demo and Fear great on a celeron. On Doom3 I have to keep on med. settings.

Given it's around $100, you could do a lot better by adding around $40 for a 7600gt - http://www.newegg.com/Product/Product.asp?Item=N82E16814130017 the performance increase is huge, you might want to try that.

As jam clearly stated, we need to know what other key components constutute your friends PC. It is not in you & your friend's best interest to expect an informed comment without that bit of information. The internet is a series of tubes!

The X1600 series is a very disappointing card. 7600GT all the way.

or if it's AGP, 7600GS/7800GS depending on budget and the rest of the system.