Windows 7: How do I get sound driver

I have a toshiba satellite L755-S521 which I have triple booted with XP, Windows 7 and Ubuntu 10.04.
The only problem is that I cannot get a sound driver for XP on this machine. I have tried numerous times. I get a message that there is no sound device on this machine.
Could anyone give me an idea of my next approach. The machine is working beautifully.

This one should work ... Model Content Page

I downloaded the suggested driver, however it did not solve the problem.
I have no activity under sound in the control panel and after installation I have a Maxx Audio Le in the control panel. Diging deeper in the installation, I ran a setup and this was the response: The NVidia setup program could locate any devices that are compatible with your hardware.
System information has no audio device
Device Manager under sound, video and game controller has audio codecs, legacy audio drivers, legacy video capture devices, media control devices and video codecs.
All I am getting are sytem beeps probably from the system speakers.
I have sound in the Linux and windows 7 partitions. What could I do next?
I am running 32 bit windows xp professional

Your sound card is actually conexant, not NVIDIA. The driver available from toshiba is for Windows 7, but I would give it a try anywho