Slow booting can be many different things. Here are a few things you can try.
First you can delete the contents of your C:\Windows\prefetch folder. The prefetch folder is used to help speed up the loading of programs by loading programs it thinks you might need. Its supposed to make your computer start faster by can actually slow it down. You can delete the contents of this folder as often as you like.
If you haven't defragged your hard drive in awhile now might be a good time.
You can also clean up your startup items using MSconfig. You may have unnecessary programs loading each time you boot your computer.
You may also have a problem with spyware installed on your computer. Check out our spyware section for solutions.