Hi Tigerintank,
Click on Start> Click on Run> Type in "msconfig"
This will bring up the System Configeration Utility.
Click on the Startup Tab and uncheck the programs you do not want to start. If its not in there have a look in Services.
From there you'll have to deceide if you want this permenant or not.
I'm puzzled as to why you want to get rid of Windows Installer, and wonder if you have some other problem?