Wrong partition info after running Diskpart Extend

[miracle_1]

after running diskpart extend, when i check on disk management, the size of my hdd becomes incorrect, from the original 6gb becomes 6.4gb

i've a 6GB harddrive from my notebook which i put in a usb HDD case.
it has 3 partition:
partition 1: 2 gb (FAT32)
partition 2: .5gb(FAT32)
partition 3: 3.5gb(FAT32)

i plug the HDD to my office computer running windows 2000 server, with service pack 3.
then i open disk management, everything show correct, then i delete partition 1 & 2 and format partiton 1 to NTFS.
then i run diskpart extend, to extend partition 1. it run without showing error.
then i open disk management, and now i have the following:
partition 1: 2.5gb (NTFS)
partition 2: .5gb (free space)
partition 3: 3.5 (FAT32)
total size: 6.4 gb

i try to fix it, plug it to my home computer running windows me. then i run partition magic 6.0 & 8.0, both keeps giving me an error that my harddrive has a wrong partition at sector XX. it give me options to fix, but there is so many of the error that keeps popping up, i've press the fix button for around 50x and eventually i gave up.

please advise me on how to resolve this problem.