There are utilities (Like Partition Magic) that can do this but before you bother I don't see why you think that it will help performance. By the time Windows (Assuming Windows) has got to even a few gigabytes (or less) your PC will be 'thrashing.' That is to say Windows will be spending so much time paging to and from disk it won't be doing any productive work.
To improve performance on a computer there is NOTHING to beat real memory. So, if you are running XP SP2 ensure that you have at least 512MB. Second ensure that you have de-fragmented your hard disk a few times. Third get rid of any programs that you don't use and may be loading 'stubs' at boot time.
t, May 2007
