A VGA or better graphics adapter is required for running VIS. For best results, you must configure your video to run in 16 bit or 24 bit (truecolor) mode. If you are buying a new system, be sure to get an adapter that utilizes the PCI or AGP interface for better performance and one with at least 4 MB of video memory for running at the higher resolutions.
If you are working with just a few images or movies clips at any one time, you'll probably want to configure Windows to run in 640x480 resolution so the images will appear as large as possible.
If you wish to record the computer screen back to video tape, you should consider a video card with a built-in scan converter which allows video output to a TV or VCR as well as a standard computer monitor.