So if you find that your inexpensive EIDE drive just can't hack it you'll need to invest in a SCSI controller and a few very large, fast hard drives. If you really get serious about video then you might consider stepping up to a RAID system, but we'll leave that for now. As far as the rest of your system goes there isn't that much you'll need beyond an average CPU (300-400 MHz or better) and a fair amount of RAM (128 MB for Win98, 256 MB for Win2K or NT). Since most video capture systems bypass the graphics card completely and simply overlay the video on top of the signal just about any graphics adapter that can handle today's games should be fine for a video capture system as long as it supports Direct Draw hardware overlay. Video on the motherboard (particularly AGP setups), ATI All-in-Wonder cards, and the original Matrox Millennium (not the Millennium II) can cause problems for video capture systems since they tend to steal PCI and memory resources. This problem can also occur with high-end sound cards, DVD cards, and Ultra66 cards. Network adapters can also cause problems during video capture since the adapter and the CPU are constantly talking to each other. If you absolutely must have your system connected to a network then you should probably go with NT.
Finally, there are a number of older systems (and a few new ones), chipsets, processors, and peripherals that don't play nice with IRQs and memory boundaries. Sometimes, a little IRQ tweaking or getting the latest and greatest drivers will solve the problem, but the naked truth is that some configurations just won't work for capturing and manipulating video. I've heard reports that Compaq Presarios with built in FireWire, Sony VAIO's, HP's with built-in AGP graphics, IBM Aptiva's with built-in MPEG, and old Packard Bell computers all have problems with video capture systems. Also, Pentium Pros, AMD K5s, Cyrix P120/P150s, and OverDrive processors for Pentium 60/66/75/90/100s are not recommended.
Other than the capture board, the proper software, and your computer, you'll probably find that the most expensive aspect of building a video capture system is all the video equipment. You can spend a small fortune on a good camcorder and VCR (to supply all that video to your new board). You'll also need tapes, camera batteries, tripods, miles of video and audio cables and adapters, a TV set (to view that video during editing), perhaps some basic audio equipment (microphones, mixer, equalizer, etc.) and a million other small things that can quickly drain your bank account.
I'm not going to try and recommend which camcorder to buy but I will mention that DV and Digital8 cameras are a little different and require a special kind of capture setup. If you're going out shopping for a new DV camcorder then look for one with IEEE 1394 connections and external control features. Many DV capture systems can connect directly to the camcorder and control functions such as starting and stopping, frame accurate searching, etc. This can be very handy for batch processing and non-linear editing.