Another multibooting option for the FAQ

I just realized this one recently. Most modern BIOS allow you to press
a key on the POST screen and choose a boot device, even a specific
hard drive.

All of the current multiboot options in the FAQ describe methods for
use with a single disk. An alternative then is to install Windows on
the first disk which the BIOS boots to by default, and then install
OpenBSD on a separate disk in the same machine. Simply press F10, F12
or whatever key your BIOS uses and choose the OpenBSD disk as your
boot device.

This method saves you the trouble of messing around with partitions,
bootloaders and potential data loss, assuming you have an additional
drive, room in the case to install it and a BIOS that supports the
option to choose an alternate boot device.