Vista.. Issues with MSI and renaming files causing high blood pressure

Running Vista Home Edition with two Admin accounts for myself and wife. Evidently I hosed up my Microsoft Installer, as everytime it boots I get the MSI trying to install various programs it canot find. I can clear it by hitting "cancel" many many times which has become annoying. Also gives me issues when shutting down.

Figured out through research that I hosed up the MSI and I need to rename the MSI files ( to .old), download a fresh MSI from Microsoft, and that should clear the issue up.

Here is where Iam stuck. I canot rename the files as it tells me I dont have permission. clicked on "run as Admin" with no help. got into security and tried to change my permissions but everything is greyed out.

Read a little on opeing upthe "built in Vista admin" but it appears you have to get in and edit the registry which is one area I want to stay away from all together. I just need some help on how to obtain the ability to rename these three simple files so I can download a fresh copy of MSI.

Thanks in Advance