GT or XT

XT is a weak cut down version (same performance as an 6600gt): AVOID it at all costs (it's a typical XFX marketing trick) !!
GT is an upper version of the vanilla 6800

Performance: 6600 -> 6600gt -> 6800XT/6800LE -------------
--------------------------------> 6800 -> 6800GT -> 6800Ultra :wink:
 
The XT usually has only 8 ROPS while the GT has 16. In addition the common XT is clocked lower than the GT which makes it even slower. The only reason to go for the XT is, if it´s offered dirt cheap. And really dirt cheap.
 
XT is akin to the LE (light edition). It is a reduced-performance card.
6800XT performs somewhere in between a regular 6800 and a 6600GT.
At this point, 6800xt is a very budget card that I can only recommend for those on a very small budget or fairly old rigs (<2Ghz P4 I'd say).
6800GT is the clearly superior card, if the price is decent it's still a good AGP upgrade path for an older system.

There are other options in AGP however, including the 7600GT or the x850 series. Often these are priced less than a 6800GT (which should be hard to find in AGP nowadays), but yield better performance.

Browse around the GPU forum to get a good idea of what to aim for, and use Tom's charts to compare relative performance.


Cheers