HardOCP published their review of the ATI Radeon HD 2600 XT graphics. They conclude that the card isn't really good for gamers but that it fits nicely in a HTPC system:
The ATI Radeon HD 2600 XT is simply not a good value for gaming. For the same price, you can buy a video card producing a better gaming experience. The 2600 XT is too little, too late, and does not offer sufficient performance to challenge NVIDIA's 8-series market domination. Conversely, the 2600 XT offered us an incredible HD movie experience with its UVD engine performing better than expected, so this may very well be the card for you HTPC users. Gamers however will be better off going with an NVIDIA based 8-series video card.