Thanks for the reply mate.
I don't know, I think I'd need a new CPU aswell. It's pretty old, I'm just not sure if I should upgrade the Mobo and RAM, or if they'll do me for a few extra years.
I'll probably get the 5770 though, that or a 4890 since it's not that much more expensive nowadays.
Also, the PSU is barely over a month old... definately not replacing it yet!