Before we start, by default, there is a 20 second delay in shutdown of Vista, a process that vista has set in order to allow software to shutdown correctly. You can adjust this to a much shorter time, thus significantly reducing the total time it takes to shutdown your computer.
1. Press the Start Orb (bottom left and then go into the Run command (remember Windows key + R).
2. Type 'Regedit' (without the quotes) and hit enter.
3. As the Registry File is so large, Im going to ask you to go top right and maximize this to full screen...and follow me.
4. Click the little triangle to the left of HKEY_LOCAL_MACHINE/ SYSTEM/ CurrentControlSet/ Control.
5. Click on the "Control" Folder. Select "WaitToKillServiceTimeout" Right click on it and select Modify. The default value is 20000. Setting it to a lower 4 digit value, say 5000
6. Simply exit when done.
The 20000 signifies a 20 second delay wheres 5000 signifies a 5 second delay. I cut 20 seconds off my shutdown time by changing this as it suggests so don't try and figure out exact time reduction by numbers...just play with it bit by bit.
You may want to remain at the 5000 mark as Vista does need time to shut software down. If this is not enough, come back and increase the size.