I got 2 external hard disks (500GB each) and using them for backups of raw home videos. I want these 2 disks to be accessible by both my iMac and 2 other Windows XP Pro and Windows Vista notebooks. Does it matter how I format the hard disks or am I constrained to format them in FAT32 format only? If it has to be FAT32 format, will I be allowed to work with larger than 4GB files? Thanks for help.