turn the pc on so you get the prompt 'grub >'
and give the command 'root' with no parameters.
this will tell you what default root is.
if its anything like mine, it will be (hd0,0)
which translates to /dev/hda1 (mounted as /boot/ on my system after bootup)
anyway..... Boot linux, have a look inside the grub root partiton (/boot/ ?)
there is a grub folder correct ?
inside the grub folder there is a file called 'menu.lst'
slap in there whatever you want to boot...
the syntax is as follws
rootnoverify (hd0,0) (the windows disk)
chainloader +1 (use windows own boot-loader)
root(hd0,0) (the disk and partiton where the kernel lives)
kernel /path/to/vmlinuz ro root=/dev/(linux root partiton)
initrd /path/to/initrd (optional)
leave out the boot command.