Get one of these, whatever you can afford :
RADEON™ 9800XT
RADEON™ 9600XT
ALL-IN-WONDER® 9600 PRO
RADEON™ 9600 SE (I wouldn't recommend this one, as it is supposed to be crap)
According to
http://www.atihl2offer.com/ , you will get a free copy of Half Life 2 with it.