I second mcangeli on that. If you don't want to mess around with you MBR, just install the bootloader to a floppy. Or, just make sure Windows is setup to boot by default, that way unless someone interviens, it will boot to Windows.
Here is a pretty good tutorial on making a boot floppy for Grub:
Or here is a pretty good rundown on how to multiboot with the Windows Boot loader:
Let us know if you run into any problems!