My defragmenter will not work in xp?

[Lon]

I must use ez-bios in order for my older computer to
accept a larger hard drive. After installing the xp
operating system I find that the defragmenter will not
work. Does anyone know of any remedies that I might
employ to get the defragmenter to work? or is their a
patch that i could download to make it work? or should I
just get another defragmenter? Any help would be much
appreciated.

Thanks,