Logitech MX510 Mouse PS/2 Drivers

Background, I'm somewhat of a techie, not much. Been playing around with Windows 7 recently, 64 bit. Just need some help/advice.

I have an old Logitech MX510 mouse and I wanted to install the Logitech software so I could program the buttons. Turns out Logitech doesn't offer anything past XP. So I downloaded the XP versionof the software and ran it on my Windows 7 in compatibility mode for XP (SP2), as administrator. Everything installed, but the mouse software didn't work. Windows driver was overriding Logitech, probably because it was more recent.

So I tried uninstalling the logitech stuff seeing as it didn't work. Unfortunately I got an error saying I was missing a file i8042prt.sys and therefore the software could not be uninstalled. Hm, I looked up the file and supposedly it should be in Windows/System32/Drivers. I didn't have it, so I thought I'd be smart. I copied the file from my old Windows XP directories and pasted it into the correct location, ran the uninstall, and everything was removed easily. Cool, so after that was done I thought that well I shouldn't leave a random file around in my systems folder so I tried deleting it.

Turns out, I couldn't delete the file I had pasted (i8042prt.sys) because I no longer had permission. As administrator this was kinda weird so I looked at who had permission. Only System and TrustedInstaller (I'm guessing this came from the Logitech software installer) had full permission. As admin, I could only read and execute. Looked around at some of the other files I have in my Drivers folder and the permissions were all similar. Administrator didn't have permission for most of the files, but TrustedInstaller did.

So...anyone know if this is a problem or anything? Everything seems to be working fine...but it kinda irks me that even as admin I can't touch many files. On a side note, I'm curious to know if the i8042prt.sys file was there originally and got deleted or if it's only there because I put it there. I would appreciate if anyone running Windows 7 could check and lemme know.

Edit: Also this is still a pretty fresh install, so no system restore points before the incident.