You can check to see what programs are loading at Start Up by using the msconfig command in your run prompt (click Start, click Run, type msconfig in the Open box, and then click OK)
Try disabling some of the unecessary program to see if that will speed things up. Also remove any useless programs from the startup folder in the start menu. I would also look at what unecessary services are being started automatically by Windows (go to control panel>administrative tools>services) and disable any services that do not need to be started automatically.
You may also want to try a defrag on your system and check for any viruses and malware/spyware. Are you up to date with your anti-virus programs?