I want to switch distributions and don't want to mess around with the Win 2K MBR recovery. Well, my Win boot sector is in turn a boot loader that loads either Win 2K or Win 98. So if I run the MBR recovery from Windows I might lose that Windows dual-boot (will I?)

How do I configure GRUB to run a diferent distro, or how do I configure it to no longer launch my current Linux distro (so that I can format the Linux partition and install another one).

Do you have a separate /boot partition? If so just leave it alone for now, and don't erase it when you install the new distro...

When you do install the new distro, do not install a boot loader (grub). The install will have created a directory '/boot' with your new kernel. Run 'mv /boot /boot.new' .Now you just need to mount your _old_ /boot partition, update fstab, and update grub.conf to boot the new kernel (don't forget to move the new kernel from /boot.new to /boot).

If you don't have a separate /boot partition then you will have to reinstall grub...no choice, however, if you back up your grub.conf it will be easy to get your old settings back....