C:\windows\s3iscfg.log,error upon videocard driver installation...

Try to install it in safe mode. How do you know when a politician is lying? His mouth is moving.
What is the exact error message you're receiving? What OS and service pack are you using? What kind of machine is it (Dell/HP/etc.)? Try going to the Microsoft site to search for the proper driver:
http://windows.microsoft.com/en-US/...Or, you can get them directly from S3: http://www.s3graphics.com/en/driver...
