ATi Overall
Pros:
Better IQ(image quality)
Can Do HDR + AA (together)
Good Price/Performance
Cons:
High Noise and Heat
High Power Requirements
Drivers
ATi Cards To Note
(anybrand)X1950XTX
Pros:
Best Single Card Solution
New Cool and Quiet Cooling Unit
Cons:
Current Driver Support
Price/Performance compared to an x1900xt
Single Card That Takes Up Two Slots
HIS X1900XT
Pros:
IceQ3 Cooler Makes The Card More Cool/Quiet Than Stock x1900xts
Best Price/Performance Card
Cons:
Power Requirements
Single Card That Takes Up Two Slots
Nvidia Overall
Pros:
Cards Run Cool and Quiet
Drivers
Low Power Requirements
Lifetime Warranties From Many Card Compaines
Cons:
Cannot Do HDR + AA (at the same time)
Lower IQ Than ATi Cards
Nvidia Card To Note
eVGA 7950GX2
Pros:
Most Powerful GPU Setup
eVGA Step Up Program
Cons:
High Price
Quad SLI Isn't Optimized
eVGA 7900GTX
Pros:
eVGA Step Up Program
Equal Contender To The X1900xt/x
Cons:
Single Card That Takes Up Two Slots
XFX 7950GT
Pros:
Passive Cooling For Complete Silence
Comes With Ghost Recon Advanced Warfighter (hehe)
Powerfull Single Slot Card
Cons:
Loses To The Cheaper Priced X1900XT In Many Benches
I think that is a pretty good break down if i do say so for myself