First make sure your windows is set not to hide "protected oporating system files" (by going to Control Panel\Folder Options\View tab, and ucheck the "hide protected oporating system files" checkbox)

Edit the boot.ini file in your c: drive, so that the timeout value will be "0" (timeout=0)

This will make your pc skip the os selection menu on startup.

If you ever want to use your other os you can change the value back to what it was in the first place.