First, uninstall the 3dfx tools (if you have a non-3dfx card the same principle applies. Any kind of utility or tool for the video card needs to be uninstalled).
Second, go into the device manager and set the video card to "standard display adapter VGA."
(1) To set the adapter to standard VGA, right click on the "my computer" icon and choose "properties" (or press the Windows hotkey and pause at the same time). This will take you into the "system properties."
(2) Click on the "device manager" tab, click on the plus sign in front of the "display adapter" category.
(3) Now double-click on the display adapter listed, then choose the "driver" tab.
(4) Now choose "update" or "change" driver (depending upon which version of Windows you have).
(5) You will then want to choose the options "display a list of all drivers" and then "show all hardware" to bring up the Windows list of manufacturers.
The "standard display types" are at the top of the list. The "Standard Display Adapter VGA" is the first one in this list. After choosing this adapter, if you have Windows 98 you will get a warning message. Disregard it and choose "yes." The Standard Display Adapter VGA will only give you 16 colors and a 640x480 resolution.
(6) You will now need to reboot to make the change take affect (Windows will prompt you to do this).
After rebooting into Windows, you'll be in 16 color mode.
(7) Shut down and install the new V5. Be sure to unplug the computer and ground yourself by touching one of the screws inside the case before touching any other components inside the computer.
(8) Power the machine on. If Windows detects the new card and wants to install drivers for it, press "no" or "cancel."
(9) Autorun the CD and install the drivers.