Installation help

[thethinkid]

Once again, I'm having deft technical trouble with my computer. Today I purchased the game Rome: Total War and when I try to install it, it gives me the error message 1607. After trying everything that the troubleshooting guide suggested, I figured out that the Windows Installer isn't installed properly, so I have to install it. Could someone help me out with this?

Edit: Also, I need to know where to find the file setup.exe