Shopping advice

If you shop around you should find the hD4650 for about your budget but it's not a very strong card.
If you can put a bit more cash into the kitty look towards the HD4670, it is a markedly superior card and about as much as the PSU can handle.
A few places to look: Scan, CCL, Dabs, Microdirect, Novatech, Pixmania and Ebuyer but there are plenty of others;)
 
Apparently that equals $46 dollars.

zibizibi, I recommend the HD4650. It will be perfectly fine with your PSU (I use it with my 200watt), and it will run Tf2 VERY nicely. 40+ frames on all high settings with anisotropic filtering on 1650x1080. Your PCI_E slot will not be an issue with the card either.