Boot your computer with a bootable XP CD and delete all the partitions and creat a new partition, then format using either FAT or NTFS.
You can also, boot the computer using a win (98, ME, 2K, XP) boot disk and use the fdisk command to delete all the partitions and then create new partitions. Then use format command to format and install your new OS!
i think i should've specified that i dont want to do anything to WIN ME and FAT32 partition. all i want to know if how do i format that NFTS partition with WIN XP on it , so later i can install xp from WIN ME again.