IF you are running XP, it is already NTFS.
What you need to do is reinstall XP. Backup your data when it asks (It should) and reinstall XP.
No, I believe you are wrong. You can have a FAT32 drive under XP. You can also format an original FAT floppy but without boot files.
For information on FAT32 formating under Windows XP, visit this link:
http://www.microsoft.com/resources/documentation/Windows/XP/all/reskit/en-us/Default.asp?url=/resources/documentation/windows/xp/all/reskit/en-us/prkc_fil_cycz.asp