Changing grub settings on the fly

[Akash]

Hi,

I have ubuntu 7.04 running vmware. I run a windows virtual machine
which boots is set to book from the physical disk.
All that works fine. My menu.lst has the following configuration

timeout         100
#hiddenmenu
default         saved

title           Ubuntu 7.10, kernel 2.6.22-14-generic
savedefault 1
root            (hd0,5)
kernel          /boot/vmlinuz-2.6.22-14-generic
root=UUID=820f4aca-7973-4c02-8fa0-65eae9fc450f ro quiet splash
initrd          /boot/initrd.img-2.6.22-14-generic

title           Microsoft Windows XP Professional
savedefault 0
root            (hd0,0)
chainloader     +1
makeactive

With this once ubuntu boots the next default target is Windows and
vice versa. The problem comes if for some reason ubuntu doesn't boot
completely ( power outage ) and now the other default is set to boot.

What I would like to do is once I have successfully booted into ubuntu
run a command like grub-set-default. But this doesn't make the change
till the actual reboot of system. I was under the impression
grub-install /dev/sda will make it work but the change is not
reflecting unless I reboot. Any suggestions for this.

Sorry for the long email.

-- 
regards
akash