Grub

I use Grub to boot up my various OS's. Its default is set to ubuntu but how do I Change the default to something like windows which is listed in the "Other Operating Systems Category"?

Open /boot/grub/grub.conf in $YOUR_EDITOR. There should be a line that says something like default=0. Change that to the appropriate index, for example if Windows is 4th in the list put default=3 (it's zero-based).