Vista - best format for a backup hard drive

I have just repartioned an old ide hard drive which has a very small partition with XP on and i now have a large partition on the drive that i want to use as a back up drive. What format is the best for backup? I have heard that FAT32 is good and it also means it can be read by OSX if the need ever arose (could be useful because my flat mate is a mac user).

Any suggestions?

NTFS is best for large drives. You can also assign user rights to it. FAT32 would use large sectors and not efficient.

NTFS is the best format, all the windows operating system later to XP can only recognize this format. Moreover as Guru has said it is best for the said reason.

You can still use FAT, FAT32 or NTFS on XP to Vista. Floppies are FAT. Smaller drive can use FAT32. It is not secure because you lose NTFS security. NTFS can format 512 byte sectors for most efficient use of the drive.

OK. Thank you for the (very prompt) advice. I will bear it in mind. I have just spent the last 3 hours putting XP back on and getting it just how i want it so i cant be bothered doing anything else tonight. I job for tomorrow i think.