what extension do you have on the files? .exe, .msi (I think that's it...
?
Could be updates, but even that wouldn't mean that many.
One thing to check; see if the extension is used by any other program.
For example: a .mat file can be a Microsoft Access file, or
it can be a material file in a program called Bryce. Both end in .mat.
Just make sure you're not erasing something you need later. However, it does amaze me how many files wind up on a system; I have over 100.000...