Some programs have an internal option to have it automatically launch when Windows boots, but regardless of whether they do or not you can use MSConfig to disable programs from starting with Windows. Just go Start->Run, type in msconfig, and press OK. On the next window select the Startup tab and uncheck the box next to anything you don't want to load automatically. Just be careful not to disable essential software.
When you reboot you will receive an alert that you are running in 'selective startup mode'...just check the box not to remind you again and click OK.
Hope this helps,
I have Windows XP, and need to keep a bunch of programs on my computer that I don't use often, but when I need them, I need them for my job. (Like SPSS, a statistical analysis program, my Roxio program, etc.) All these programs apparently load when I start up my computer, and make the system slow to boot up and slow to run. How can I keep the programs on the computer, but have them available only when I need them, and not have them load (or load partially, whatever they are doing) when I boot up?