Back when I was running Windows XP I found a file called  Dr. Watson log. I noticed a lot of space was missing on my Hd and couldn't figure out why. So I started to look around and found this. 

C:\Documents and Settings\All Users\Application Data\Microsoft\Dr Watson 

inside was a 3gig log file !!! 

looking further into this I found that Dr. Waston saves all app errors to a log file and can grow to a HUGE size 

to access the Dr. Watson utility goto Start&gt; Run&gt; and type in drwtsn32 
from here you can clear this file and configure it so i won't grow to a crazy ass size. 

Just figured I would post on this just incase others out there never checked this out before. There could be lots of space to free up! Especially if you have ran XP for years without reinstalling like I did.