Finally thanks to driverpacks.net forum I have found sound card driver for my Dell XPS 430.
Sadly but Dell has built driver for this card to works only on Windows Vista and on IDT site it’s impossible to download drivers because they have such agreement with OEMs that they cannot provide drivers by themselves.
Pukkita has modified one of the IDT sound card drivers for Gateway and it works on my Dell.
Link for download you can find on Pukkita’s blog as well as Paypal Donations link.
If you don't already have a Dropbox account then you can create it by clicking on my affiliate link. You will receive 2GB free account + 250 MB extra and I will receive 250 MB as well. Win-Win :-)
Tnx Kris.
I have abandoned this solution after Vista SP2 has arrived and returned to Vista. I think it works much better now, it’s much more stable and so far I didn’t have had any problems at all.