Pick up a 7600 GS or something like that. It's a recent generation card that has relatively low power consumption, decent performance, and won't break the bank. Although....a 7300 would probably even do the trick.
Any of those would be fine for a "non" gamer card. Just a shame that you have a good CPU and Mobo and don't take advantage of it, but it's not mine. If you want Dx10 card, so you can use a 64bit Vista (assuming you would want to), than any of those that you mention would work for that. And if you want to eventually want to play a game later, than you can come back and ask more ?'s if you like. Enjoy your system!
Surfing the net requires no more than a Tesco built rig. Pc world can get u an online ready Pc for far less than buying low end pieces. I agree with previous posters about your mobo + processor. Who told you to buy them for just surfing the net? But its your rig, I know its an english site but