From what I read, you could uncheck the GRUB installation, that is don't install it at all. If your main boot loader is GRUB2 you could boot the other main system, update-grub, it will pick up LMDE's installation, then you reboot into LMDE, install the available updates and one of them will be GRUB, then during the upgrade it will ask you where to install it and then you point to the desired partition/drive.
Thanks for the reply. I thought about your advice and came up with a solution or work around until this is fixed. I have Windows XP on my first hard drive, and now, Linux Mint Debian on my second hard drive. I use gag on a floppy to access which one I want to boot; no Linux on Windows drive, no Windows on Linux drive. What I did was install Mint Debian on my second hard drive. When it came to the question about installing grub in either sda or sdb, I chose sda. Bear with me. I then booted up the system without using my floppy (gag) and sure enough, mbr had been written over in the Windows system. I chose to start Mint Debian. I then did the updates, which took awhile to download. As it was installing them, it did ask me where to put the updated grub. I did have the option to put it in the root partition of my Mint install; in my case, sdb2. I then restarted my system, this time using my gag floppy and all worked great. I restarted again to check and see if the Windows mbr had been corrected to boot just Windows; it had not. I then grabbed my bootable Windows start up floppy that I had made and restarted the system using it. Brought up the prompt to start with cd support, or not. I chose not. Eventually got to the A:> prompt and typed: "fdisk/mbr". This rewrites the mbr on the Windows box. Restarted the sytem (without the gag floppy) and whola, Windows started and grub was removed.
I know that this is rather lengthy, but maybe it will help someone out. I asked for someone to help me through this and I just hope that this helps someone also. If you have a different version of Windows, you might have to do the restore mbr in Windows a little different (use the cd rather than the floppy), but it can be done.