Is it safe to delete these folders?

When transferring files to an external drive, I came across a lot of folders in the Windows directory. They all have similar names:

$NtUninstallKB821253$ folder which contains: spuninst, fp4autl.dll, fp40ext.inf

$NtUninstallKB824141$ folder which contains: spuninst, user32.dll, win32k.sys
etc.
I have about 150 of these folders and I suspect that they are just left-over junk and that they are the cause of my computer running even slower than I do.

Is it safe to delete these? None of the "clean-up" programs I have tried have done anything about them.

Thank you for your help.

 

Yes, it's safe to delete them. They are backups for any hotfixes (Windows Updates) you've installed. They are used for uninstalling the hotfixes if necessary. So, as long as you don't have a need to uninstall any of them, you can delete those folders.

I delete them once I'm sure I don't have any problems due to the update. I usually keep them around for a month or two, then delete them.

One thing though. Don't mess with the $hf_mig$ folder. Windows uses it for reference for future updates.

http://support.microsoft.com/kb/824994

Here's the relevant part from the article.

So, if you delete that folder or the folders in it, in future updates you could end up installing older versions of some files, possibly undoing whatever security fix that the overwritten file contained.