I want to turn my old TiBook into a file server for my LAN. Looking for a PCMCIA eSATA card. I would like to hook up at least 4 drives, but all the cards I see have only 2 ports. I've heard of port multipliers, how do those work, and do they work with all controller cards & drives? What is the difference between eSATA and SATA? Are all eSATA PCMCIA cards compatible with Mac OS X? Will I need to install a driver or will they work out of the box? Any recommendations on a card to buy, and a place to buy it from? Thanks!