HD space issue
I have an older PC which has a 10GB hard drive in it. I have XP Pro as its OS. I also have the following programs on it that I want on it. Peer guardian 2, Ghost surf 2007, threatfire, malwarebytes antimalware, Diskeeper 2009, Orbit, Imageburm, Super antispyware pro 2009, revo uninstaller, winzip. When I go into add/remove programs none of these things look like they take much HD space. Out of the 10GB I have roughly 1.5 GB free but would like to free up more but I can't figure out what is using all of this space? Can someone tell me where it all is? I cleaned up all my cache so it is not that. I appreciate any help given.
PS. I know HD are cheap but not for this 10 year old PC