Well, it doesn't actually have to be a TV tuner... could be something geared specifically to analog video capture (I think certain high-end firewire add-in cards also support analog video capture).

For that matter, if you have a camcorder with firewire output, some higher-end models can take an analog input and convert it to a DV/firewire stream. My not-too-expensive Samsung can do that. You'd still have to reprocess that to MPEG2, but if you have a lot of editing of your VHS source to do - say take out commercials or remove the chaff from your home videos - it may end up being better.

I recently did just this to a relative's 1980's appearance on a TV show... I tried the camcorder/firewire route, but ended up capturing via my ATI All-In-Wonder video card (built-in TV tuner and analog video capture) to high-bitrate MPEG2 (out of DVD spec), then edited those files, removing commercials and so on, outputted them as lower bitrate MPEG2, then created a whole DVD around them with animated menus and so on.

The whole project, with about 2.5 hours of source material, took about 2 nights.