I'm working with a computer that has XP installed on a FAT formatted disc partition and I want to upgrade it to Vista. The Vista installer would not allow me to perform an upgrade install because it ...

Apple computers configure hard drives differently than Windows computers. Windows uses NTFS or FAT32 as their native file system while Apple uses HFS+. Apple does not support the NTFS files system but ...

You can't go back to FAT32 without formatting. At least not natively in Windows. Perhaps there's a third party tool somewhere that will do it. You want to go from a modern, hard linking, journalling, ...