I just got this card as well on amazon. my system spec is smiliar to yours
window xp 32 bits
However, I did not see huge improvement went I install the card, I took my computer to Microcenter . The tech there did a computer check up. They overclocked my stock CPU a bit and added 2gig of Ram only charged me for the RAM. the performance shoot up dramatically.
I think you need more RAM to go with that card and a slight OC.