S3 went out of business in the late 90's. No drivers were ever written (for Windows XP) for S3 products that I'm aware of. You might find drivers written for Windows NT4 and Windows 2000 that will possibly work in Windows XP.
I couldn't find this driver for Windows OS's (found one for Os2) on this site:
There are drivers for older Windows OS's posted in our driver database here:
But none are for Windows XP.
S3 86C764X = Trio 64