For Advanced Users Only
This is not for the inexperienced, nor for the intermediate-level user. Don't attempt this if you don't fully understand what is being done, and where, and why. Read through these instructions very carefully, and print them for reference. If you're confused by any of the instructions, don't attempt the procedures. If you're uncomfortable working in the system registry, don't attempt the procedures.
Be advised that Microsoft does not support this configuration, even though the MS Knowledge Base has explicit instructions on how to perform the proper steps in the correct manner. However, if you do understand how it can be done, and you have a desire to clean up and reorganize your machine, you can configure XP to run your way. I've seen a number of posts in various help forums on the web asking questions for which this information might be a useful answer, in whole or in part.
Before attempting any of these procedures, do a full system backup, preferably drive image(s).
I won't go through "how to partition and format a hard drive" but if you haven't set up the partitions necessary for this customization, here is a link for a good practical guide. If you have not partitioned your drive (that is, it's still just one big "C:" drive), the Windows Disk Management tool won't allow any changes to the system root partition. However, it can be reconfigured using third party software. My favorite is BootIt Next Generation, from Terabyte, which is also a boot manager and a great disk-imaging tool, among several other uses. Well worth the $34.95. There is a fully functional 30-day free trial download available; try it before you buy.