Yeah could be the difference in drivers for the card. I'd check the newsgroups or one of the forums on some of the more PC Tech related sites. I just have the SBLive Gamer I think one of the cheap ones so I do use a different Driver than you.
Maximum PC or Ars Technica both have really good forums and people usually get beta drivers and post it on a personal site every now and then, check those out I fixed my DX8 Geforce problem with a beta driver from someone with an early release, but again its beta so it could do more harm than good.
-Shane