After clicking on "OK" Vista's nagging permission screen will show up and click "Continue". You can also go to How to disable Vistas nagging permission screens with Vista4expert to learn how to remove these.
After clicking on Advanced options the BOOT Advanced Options dialog box will show up.
Click on the the box that says "Number of processors" and select how many cores your processor has.
Click on "OK" and then tick the "Make all boot settings permanent". This will make windows use the option we made every time that the computer boots up.
Now press "Apply" . A warning dialog will pop up just press "yes" and then finally press "OK" to close out the System Configuration Utility.
My personal results have been a decrease of about 20 seconds but since all computers are different individual results may vary.