I've got both a Dazzle DV bridge and a Canopus ADVC. The Dazzle has worked with every PC or Mac I've plugged it into, but it seems to be a bit flakey at times (for PCs, won't auto sense the type of conversion being done - need to use the toggle button before doing anything, for both PCs and Macs, it doesn't do locked audio so it will get out of synch after a while (after 10-20GB of capture)). The Canopus is great with locked audio and really a nice product, but it's never worked with my desktop Mac (dual g4 1ghz, non MDD). Works great with my newer PB17 though, so who knows.
Get one of those 2 ($250ish, more in ¥ or £) and try it with your setup. If it doesn't work, take it back and get the other.
(Or! if you have a DV camera with line ins, just set it to passthrough or line-in-VTR mode and use that

)