Because upgrading Windows tends to overwrite the boot loader, if it is installed in the MBR, the best location for installing the bootloader is the boot partition or, if you are installing to a second hard disk, the MBR of the second hard disk. Doing that will ensure that nothing you do on Windows will affect the Linux or BSD installation.
This article presents a step-by-step guide on how to dual-boot Windows 7 and Debian 6.
