Try defragmenting your hard drive. Download Microsoft Bootvis and run it. It helps (I shaved a few seconds from that).
Go to Start > All Programs > Startup and delete all the stuff there. What that does is clear out the programs that start up when you login.
After that, go to Start > Run > type "msconfig" and click on BOOT.INI and find the box that says "/NOGUIBOOT" and click it. That takes out that Windows XP flag and loading bar we've all seen for the past 5 years. It also speeds up boot time.
Go to the Startup tab and uncheck programs you know you won't need at startup. That will save time.
Go to the Services tab and uncheckmark the programs that you know you don't need either. If you're not sure which ones are vital, click on the box on the bottom that says "Hide All Microsoft Services" so you won't accidentally prevent some critial OS program from starting.
One of the most basic things is to just to a complete anti-virus and anti-spyware sweep of your computer. Those buggers also slow down your computer's boot time and performance.