First - why would you want to?
NTFS has many features that you cannot get with FAT32.
FAT32 gives only a couple of "benefits" over NTFS:
- You can boot with a normal boot diskette/CD and read the information on
the hard drive
- slight (very very slight - likely nanoseconds) speed difference over NTFS
But, if you have some decent reason - you will need to get a third party
tool or format and start over.
