maybe this is what you want
if you don't want to mess with your MBR (and risk not being able to boot into Window$), then simply install grub into your Linux partition's MBR like so:
A) enter the grub shell.
B) type "root (hdx,y)" (without the quotes, of course) and hit enter (replace x and y with the partition that your grub files are installed upon).
C) type "setup (hdm,n)" (without the quotes, of course) and hit enter (replace m and n with the root partition your Linux system).
D) quit the grub shell.
E) type "dd if=/dev/hdhk of=~/linux.bin bs=512 count=1" (without the quotes, of course) and hit enter (replace hk with the root partition of your Linux system). You will now have a 512-kilobyte file in your home directory named "linux.bin".
F) copy "linux.bin" to somewhere where Window$ can read it upon boot (the c: might be a popular choice).
H) edit the Window$ file, "boot.ini", and add a line that says something like <c:\linux.bin="Linux"> (without the braces, of course).
I) reboot and enjoy.