it all depends on your CPUs compatibilty. i had nothing but problems with the ATI cards. for 2 years i had an ATI card problem and nobody from their tech department would help me out. any game i played over the internet was crashing after 5 minutes of play. later i found out that i had some device interfering with the I/O or this device was draining power from my graphics card without even knowing it. i opted to try out the nvidia's and i love them.
remember this, ATI has one of the worst tech supports ive ever scene. unless they've greatly improved since their merged with Althon, dont expect any help. Nvidia has a much better system in place and they accually help you with other issues aswell.