I have a spare 750 that was just a storage device for Windows (NTFS) i formatted it to fat32 to transfer files between Windows & OSX. So no my dilemma is that OSX will not install on this drive. I did extended drive testing under both Windows and OSX. I can format it to Fat32 all day and night long. I can format it to NTFS all day and night long, transfer files back and forth and stress tested it extensively. I want this to be my main OSX drive in my spare iMac. I put it in and then i got this when initializing it with Disk Utility, using the built in OS one and the original 10.5.2 disks. I also placed this in my MacPro and the same issue. the message i get when trying to Install OSX or even formatting it to HFS+: I cant seem to format it to HFS+ (Mac OS Extended Journaled) any help, this drive has no issues or bad sectors thanks === edit/update I was able to format it into 2-partitions of HFS+ (Mac OS Extended Journaled) but i cant have a single partition....hm. Im wondering under Options in the PARTITION tab do i select GUID Partition? because if thats the case then i think it might have defaulted to MBR or something and wasnt allowing me to format it... thanks again!