I just got done building my first computer and I need a new GPU because the one I have in there now (a free card that my friend gave me) is not suffice for SC2. I dont plan on crossfiring now, but I want that option open in the future and therefore I want to stick with ATI since my mobo is only crossfire ready. I dunno where to start and I would like a card that is the best bang for your buck and that can handle SC2 on high or ultra settings.
Though you might have to upgrade your power supply when/if you decide to do crossfire.
You can also wait a month or so and see if the new radeon cards come out.
HD5770. It's not the best for your resolution but it should still be rather good. Two in crossfire will give you performance similar to an HD5870. An 550w Antec should handle crossfired HD5770s just fine BTW. http://www.newegg.com/Product/Product.aspx?Item=N82E16814102873 Alternately wait a bit for the HD6000 cards if you aren't in a real hurry.
Save a little bit and get HD5850... Yes, it's expensive, but can handle most of games with HIGH setting. but if you want to CF then you must upgrade your PSU.
is there a particular brand that is good... can you link me one?