|It's empty? Then you don't need to 'convert' it. Just boot up with the XP cd and let it load the files. It'll get to the screen that will allow you to delete the fat32 partition. Do that and recreate it as NTFS.|
You can also delete the fat32 partition with FDISK on a 98 bootdisk or the old dos utility DELPART. But neither of those are capable of then creating an NTFS partition.
Or, if it's a slave drive on a functioning XP system you should be able to delete and recreate the partition with disk management.