What's the difference between a SATA Bridge and an External USB Hard Drive in terms of the way each one functions? My Mac Book never has a problem reading external USB Hard Drives no matter what format they're in (NTFS / FAT32 or whatever else). But I'm having problems with this SATA Bridge that I have (it's basically the internal HD from my old laptop and I've put it inside a SATA to USB case). Actually my Mac Book never had problems reading the SATA Bridge until I formatted it recently (on my Windows PC) and now the Mac Book won't ever recognize that the SATA bridge is plugged in the USB. Anyway, what's the difference in functionality between the two? I've noticed this difference not only on my MacBook but also on my WDTV Media Player (if you don't know what that is, it's like an Apple TV). The Media Player can always read external USB HDs but for some reason cannot read the SATA Bridge.