Run msconfig.
Under the Start Up tab, uncheck those programs that you know you don't need at boot up (leave all the ones with Microsoft in the name).
Do this slowly, and reboot each time to make sure you didn't need it. Some drivers load via programs, so be careful.
Thing I know you can turn off: Anything Abode, Office, or any other programs you installed. Manufactures all think that their software will be needed instantly and often, as is not the case.