I am presuming before hand that you have a 400w or greater PSU ? If that is true I would recommend the GTS 450 http://www.newegg.com/Product/Product.aspx?Item=N82E16814500187&nm_mc=OTC-Channel&cm_mmc=OTC-channel-_-Video+Cards-_-ZOTAC-_-14500187&srccode=cii_7240466&cpncode=23-14360351&DEPA=0&refer=channel&CMP=OTC-
It is quite a bit more powerful than the 9800 so you won't need to upgrade to soon in the future, which will save money and for only $50 more at newegg it is a really good card. I do understand though that you said you didn't want to spend $100's and if you cant afford the GTS 450 the 9800 GT is a great card but like I said they are dying out and an upgrade will be required relatively soon.
I am sure you will be able to find a cheap GTS 450 on amazon or somewhere like that. But just confirm that
you have a 400w+ PSU (You should have).