Windows itself takes up a lot of hard disk space. Over 2 GB is about right. XP with SP1 takes up about 2.5 GB. Even more if you were to use System Restore with the later operating systems.
Could you please post what actual problems you were experiencing with your PC.
Also a reformat is a relatively easy process to go through. Just time consuming.
So please post your problems and I and other forum uses shall see what we can do.