FIXED
this error has happend to a lot of people running windows vista, I've done a small tutorial for anyone wanting to know.

When running a microsoft installer (.msi file) if it comes up saying the OS is inadequate. You have to run the program ORCA (downloadable with the windows SDK kit)

Open up the MSI file in ORCA and on the left, there will be a list, select LaunchConidition and delete all form of code there.

Save the MSI and walah!