In your menu.lst file towards the middle you will see this stanza:
## default grub root device
## e.g. groot=(hd0,0)
# groot=(hd0,0)
This part is read, with groot=(hd0,0) being the default every time you run update-grub as Timo mentioned. You will want to add 'groot=(hd0,2)' after the '# groot' part. You could also do something similar for what you want your default OS to be.
In your menu.lst file towards the middle you will see this stanza:
## default grub root device
## e.g. groot=(hd0,0)
# groot=(hd0,0)
This part is read, with groot=(hd0,0) being the default every time you run update-grub as Timo mentioned. You will want to add 'groot=(hd0,2)' after the '# groot' part. You could also do something similar for what you want your default OS to be.