Ok, I'm currently toying with the idea of upgrading my graphics card at present, mostly because my current one (8800GT) is getting fairly noisy, even after being cleaned out with compressed air. I've not really followed the very latest hardware releases so I'm not 100% sure what represents an upgrade to my current card.
One other thing to note is that my motherboard would support Crossfire, so perhaps an ATI card might be more favourable, as I could upgrade later down the line with a second unit (or even get 2 if a pair of cheap cards works out better)