I have the same problem for two computers--one belongs to my in-laws, the other to my uncle.
When they boot up the computers, they get a menu asking which operating system they want to use. How do I get rid of that?
For my uncle, his computer was virus ridden (2000+ viruses when I finally took it home and cleaned it off). Because his system was corrupted, it kept telling him to reinstall. And so he did, creating an additional menu option each time. I installed Win XP on his computer (he had Win 2000). However, because he had all those installations, there is a menu option for each of them (though they no longer work).
My in-laws managed to delete all their drivers (for sound and what not) and reinstalled for that reason. So they also have a multiple choice for operating system.
Is there any way to get rid of that menu w/o formatting the drive?