I've actually had *terrible* luck with USB cards in Macs in general, even when the card claims Macintosh compatibility. In *theory* just about any OHCI PCI card *should* work, but, they don't. Symptoms include failing to boot, bizarre performance problems when the card is present, general flakiness, etc. (All the cards involved have tested fine in PCs after being pulled from the Mac.) Again, these were cards that *said they were Mac compatible on the box* but happened to be cheap. If you want it to actually work this is one case where I strongly recommend going with the premium product, like a Sonnet Allegro card. It'll cost twice as much but at least there's some assurance that the "Mac Compatibility" involved more testing than shoving the card in one machine and seeing if smoke poured out.