Start-Run then type MSCONFIG, go to Services and Hide Microsoft Services, the remaining are services you may or may not need depending on what applications you installed and are using. You can uncheck all that are useless to you.
From there you can click the Startup tab and uncheck everything you don't need to run on startup. (some apps. will not allow you to modify this from their own control setting, might be a good idea to uninstall some, like browser bars for example.)
Like they Tigsounds said, avoid the system drivers, like video, sound and network and any other hardware you have installed.