Nearly forgot about this, sorry. Tried reinstalling drivers a while back, which didn't do much. I even did a system restore back prior to a driver update which I assumed to be causing the problem, but that didn't fix it either. Now I'm assuming it's just the TV causing the issue, which is strange considering something like a PS3 runs fine at 1080p via HDMI. I might try testing it on my 1080p monitor sometime and see if i get the same issue, if I don't it's probably just a problem with the TV which I don't want to deal with. It could also just be that the drivers are picky in terms of which devices it'll work on.
Thanks for the help.