This command requires Boot Camp 3.0 or later (beginning with Mac OS X v10.6 Snow Leopard).
1. Boot the Mac using Windows.
2. Click on Start.
3. Click on All Programs.
4. Click on Accessories.
5. Click on Command Prompt.
6. Type in the following command:
c:\progra~1\Bootca~1\bootcamp.exe -StartupDisk "Mac OS"
Shutdown /r /t 0
The computer will restart into Mac OS X.