If your computer takes too long to boot up then you might be running way too many programs on start-up.
Find out what programs run on startup and disable the ones you don't need:
Click Start -> Run -> type
msconfig and press OK
Open the startup manager and un-check the programs you want to remove from your startup.
If you need more details of your startup programs you can download
Autoruns 9.36 - a free utility that will show you the auto-starting locations of any startup monitor.