IceToad

I mentioned the System Configuration Utility as a great tool for troubleshooting startup problems. You can also use the SCU for controlling which applications get to run themselves when your system starts - even if they are not causing any problems. It seems like more and more applications want to start something up with your system, whether it's AIM, MSN, RealPlayer, etc. Some of them are important, such as your anti-virus program, but most of them just make your system take forever to boot. There are nearly a dozen potential places that a program can start itself up from when booting, too, such as in the Registry or the Start Menu. This can make it difficult to track down the origin of startup programs.
When you run the SCU by entering "msconfig" without the quotes in the Run box (Start -> Run or Windows-R), and click on the Startup tab, you will see a list of the programs that are set to run on startup, and where they load from (for instance, where in the Registry, or Start Menu). You can clear the checkbox next to them to keep them from running the next time your computer is started (or the next time you log in, in some cases). If you decide to make changes to these settings, you will notice that every time Windows starts, the SCU will also run, unless you check the box next to "Don't show this message or launch the SCU when Windows starts).