Uncheck everything. When you reboot the OS will load up what it needs to sustain.
Thats in msconfig and you don't want to do that if you want your anti-virus running or make sure that its checked.
Start menu wont really slow your computer down other then when opening the start-all programs menu.
Sounds like you need to do some cleaning of old files, temp files, prefect folder, registry cleaning, and removeing unneeded startup programs.
How much memory do you have? Less than 512 will really slow you down.