In order to transfer files easily (and frequently) between a mac pro and a PC, I have decided that an external HD would do the job best. Due to the issues and lack of support for USB 3 by Apple, I have decided that an eSATA dive connection would be best. My remaining questions are as follows: Are the transfer speeds of external enclosures limited by their own hardware, or is the speed of the drive the determining factor? Many of the product listings I've seen are ambiguous on this. If I got a SATA III PCI card, and a SATA III HD, rated at 6 GB/s, and put it into an enclosure designed a few years ago which only says it gets 3.0 GB/s, will I be limited to 3.0 GB/s? Seems to me that the enclosure ought not to interfere with the speed of the unit, but what do I know? Second question: Will I be able to switch said eSATA hard drive between my Mac and a PC running XP? I'm not talking hot swapping, just powering down, switching the connection, and powering back on again. I have a couple external USB HDs that work with both systems, so I figure it will be fine. But again, what do I know? OWC tells me that a PC won't see a drive formatted in a Mac OS HFS+ file system on a GUID drive partition. Others tell me that a Mac can read but not write to an NTFS formatted Hard Drive. So can I format it as FAT32? Is it still possible to format something as FAT32 anymore? OWC suggests getting MacDrive7 for my PC to view Mac files. That will be my solution of last resort. Any better suggestions?