Thanks for the reply guys.
I currently have the Nvidia 8800GT, happy to date so I'm planning on staying with Nvidia. Want to stay under $500 aus but hope to spend around $300. I play WOW on this PC and the fps has suffered since I started playing it again after a 9 month lay off. Getting under 20 fps. Plan on getting Windows 7 64 bit to maximise my RAM capability, as I have 4gb but only get 3.2 on my current XP 32 bit. I'm not a serious gamer, but like to not be hamstrung too much when I PVP, which is my favourite part of gaming.
I guess my OP was about trying to find out whether I need to upgrade my MBoard to get a decent Graphics card or if it can still use the latest Cards.