Reboot and hold down the option key as soon as you hear the chime (bong!). Hold it until you see a choice of what to boot from on the screen. Choose your Macintosh HD and press enter. As soon as you're in OS X, open System Preferences, Startup Disk, and choose your Macintosh HD as the default. Whenever you wish to boot into Windows, restart and hold down the option key and select the Boot Camp partition. When you leave Windows and reboot, the machine will automatically boot to OS X.