Deleting files in the windows installer folder

How do you clean up the windows/installer folder on a xp machine. I looked on different forums, but the tool many mention is no longer officially supported and from what I understand not specifically for this task. Also, I was confused on which tool to use or how to use it. The reason I ask this is I have an older computer with ~86gb drive and ~80gb of is being used by the windows/installer. I'm assuming that at least some of these are glitches and shouldn't be in there.

Note that the person who uses the computer mentioned trying to interrupt an install at some point and I don't know if this has anything to do with it. Also, there are not that many programs installed on this computer ~25.

Also, I know that similar questions has been asked several times already, but the accepted answer Is it safe to delete from C:\Windows\Installer? is mainly talking about is it safe to delete (along with most of the duplicates). I'm asking how to find and delete the files that shouldn't be there especially since were not talking 5-10gb but something that practically fills the entire hard drive, and for those who are wondering I ran CCleaner, but it doesn't seem to check this folder.

Your best bet is to use the Microsoft Installer Cleanup Utility (msicuu). It is a front-end to msizap which can let you safely (more or less) completely (more or less) remove Windows Installer programs and all of their files and registry entries. Of course you would then have to reinstall any programs that you did want (e.g., if some program’s installer is defective and kept failing and creating new folders instead of using the same one).

If you don’t know which items to nuke, use a program like WinDirStat or SequoiaView to find out which files/folders in the Installer folder are excessively large. Then you can check the Summary tab of the Properties dialog for the .msi files to find out the product name:

I'd start with Disk Cleanup.

Then, try this: http://support.microsoft.com/mats/Program_Install_and_Uninstall/ to possibly clean up the old files. It's the replacement for msizap.exe, which might be what you were thinking of before.