GRUB (Legacy) Configuration
 

I set up a dual boot, XP/openSUSE, using GRUB.

Would like to make XP the default OS for unattended boot... how do I modify GRUB?

There are two things you can do. Both involve editing /boot/grub/menu.lst.

First:
In menu.lst, there is a line which reads: default 0

That means the first OS in the menu.lst is the default. If you arrange the order so that xp is first, it will be the default.

Second:
If xp is not first in the list (second, third, etc), then change the default 0 line to read default 1 (for the second in the list), default 2 (for the third in the list), etc.

Your choice, whichever is eaiser for you.