Also it may be a good idea to use WinPatrol. Even the free version warns you about auto starts being installed and BHOs(Browser Helper Objects.) IE BHOs can be very dangerous as they can be ActiveX based and do stuff like mess with files on your system. The only time my system got totally hosed by a Malware it was an IE BHO. After that I don't run IE. I use a simulator to see if my page looks OK to IE users. But I don't run IE itself ever.
When an installer tries to put in a BHO or change the browser start page, WP pops up a confirmation dialog. Just click No.