Niffty, Do you have a MinDV Camcorder? If so check if it can do pass through A/D conversion. This way you connect your anlogue source to the miniDV and then plug the minidv into the a firewire port on the PC. Giving you pretty good A/D converter. You can also look at the Canopus range of ADVC converters. The TV capture cards like AvertTV (i have owned the PCI and PCMCIA versions) are also a good option but you will need to look at the CODECS available. These cards as i recall use Software codecs to compress the video and this means you will need a decent CPU to use this without dropping frames. Most cheap USB capture cards also use software codecs. To get a good one that does AD conversion external to the PC you will pay more, these two will vary in cost based on the output Digital format/codec used. You can often pickup a used Canopus on ebay relatively cheaply.
This is a good website to compare various products.
http://www.videohelp.com/
Note: with faster CPU's today the USB grabbers maybe just fine for what you need. I have not used one for some time, back when CPU's where still single core.
