Sonnet makes parts just for macs. If the card is PCI it should work just fine. Sata will be faster than ata100/133. Whether or not its necessary I cannot say, but it is the way to go. I ran sata Raids in my Macs in the part and it was great. Can't remember the brand....not sonnet....I did write an article on it somewhere here on MacMod. PCI does limit drives at this time, but four of them in RAID should be just fine. The Mac softRAID has always worked for me. Find the cheapest Mac compatible card you can. Most are based on the same chip and even have the same board...some pricier than others. Had three Quicksilvers my self, great machines, but touchy motherboards. Also, if you plan a cpu upgrade, full ram, a good video card with molex, Raid card and a bunch of drives, don't forget about the power supply. It is limited on how much it can handle.