There are various sources for Windows 95 drivers for the Viper series. Finding a good one is the problem! The ones on the Win95 CD-ROM are based on the old Windows 3.1 drivers, and are not real Win95 drivers at all.
Since Windows 95 was released, there have been a series of updated Viper drivers from both Diamond and Weitek. Here are links to pages describing each driver set. The pages include (a) where to get it, (b) how to get it working, and (c) other people's experiences with them.
Windows 98 may have drivers already.