http://arstechnica.com/guides/tweaks/sgp-tweaks.ars
Found this at experts exchange
http://www.experts-exchange.com/Storage/Q_21870205.html
It mentions a registry tweak that works under XP and also a program called
PerfectDisk which has a free evaluation. Couldnt find much more on it myself
after that.
You can only increase the MFT, you can't decrease it once
it's expanded. Basic details of MFT here,
and an explanation of the available options in Windows XP which affect MFT are
in this Microsoft
Article.
If you mean artificially expand the MFT size, then really
you're better off just getting a program like Diskeeper which
allows you to manually set the size of the MFT (only making it larger though,
not smaller), and also defragments the MFT whenever you set it for a boot-time
defrag job. You can use the trial version of Diskeeper to do that for free.