Windows $PatchCache$ folder

I'm trying to do some maintenance on my Windows XP Home system. One of the
things I've noticed is that my C:\Windows\Installer folder is getting WAY
out of line. There's almost 1GB of files in that folder (and its
subfolders). I've downloaded Microsoft's Install Cleanup Utility, but I'm
not really sure which things to remove. However, my main question is one of
the folders in that \Installer folder. It's called $PatchCache$, and it
contains several hundred MB of files in its subfolders.

What is this folder used for? And can I delete it (as I'm deleting many of
the other Installer subfolders)? What are the repercussions of doing so?
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Frank D. Nicodem, Jr.