the last drivers form S3 were publish in 2000 before S3 was sold to VIA. If the card is compatible with Windows7 the driver would be available via Microsoft.
The S3 card has a maximum capacity of 4 meg of ram, pretty useless for Windows 7 use, when the current minumum is about 128 mb. I suspect the rest of the hardware is as well.
Use the Windows Upgrade Advisor before you start. http://windows.microsoft.com/en-us/windows/downloads/upgrade-advisor