John
I have NT 3.1 on one partition and Linux (Slackware) on another and can boot
either way. The key is to modify the MBR using Linux's LILO, not from NT's
control panel. Here's what I did:
a) Installed NT on the first partition. At this point the machine will only
boot to NT.
b) Installed Linux on the second partion and used LILO to add a DOS boot option
to the MBR. It doesn't seem to care that there is no DOS on the first partition
and happily boots NT instead!
You might back up any critical data before trying this, I'm not running NT
version 3.5 and there's the chance it won't.
Good luck!