With vista's new Security settings, you may find that you cannot install software using an MSI. Even though during the install process you have granted it Admin access. (thus resulting in a msg box similar to the following: )

an Error code of 2869 or similar... why.. and what the monkies is going on. Well i do not know the full reason, but I can give you a small work around

open up your exporer and navigate to "C:\Windows\System32"

right click on the cmd.exe and select "Run as Administrator"

In the newly opened CMD window (note in the top left it says Administrator) navigate to the msi setup file and run it via the cmd... this will now install the software.