The only thing I would suggest is if you can afford it go for a Sapphire x1950pro, they're £115 off scan but pack a nice little punch.
eta:
http://www.scan.co.uk/Products/Produ...oductID=481911
re-eta: but i notice you wont be playing games like supreme commander or crysis yet, so the x1650 should be fine
. When it starts to feel a little sluggish, just buy another midrange card. By then dx10 cards will be out and it will be better than forking out more now. I tend to play a fair amount of graphically intensive games at high settings so the x1950 is essential for me.