What Kind Of Video Card Do I Need?

OK, I Have A Hp Pavilion a630n (a href="http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00210099&tmp_track_link=ot_faqs/top_issues/en_us/c00210099/loc:3&lc=en&dlc=en&cc=us&lang=en&product=426322)," rel="nofollow"http://h10025.www1.hp.com/ewfrf/wc/docum…/a well, i just want a video card that will run vista or win 7, but i don't know what to search for on ebay, any help will be appreciated, i can't seem to find anything, thanks.