I reinstalled Windows XP (as one has to do every year or so), and of course it overwrote my MBR, where I had stored GRUB. What's the easiest way to restore GRUB without overwriting my menu.lst or my images subdirectory in /boot/grub?

If you have a Linux boot cd (knoppix or dsl will work), load it, and run grub. In the grub shell (assuming partition 2 as linux partition), type "install (hd0,1)/boot/grub/stage1 (hd0) (hd0,1)/boot/grub/stage2 (hd0,1)/boot/grub/menu.lst". This will reinstall grub to the mbr, and use your existing menu.

If you have a grub boot floppy, you can boot it, then type "configfile (hd0,1)/boot/grub/menu.lst" to boot from your grub menu.

Lastly, you should also install grub on the linux partition so that it can be added to Windows boot menu, with "install (hd0,1)/boot/grub/stage1 (hd0,1) (hd0,1)/boot/grub/stage2 (hd0,1)/boot/grub/menu.lst" in grub, then adding that partition to Windows boot menu (don't ask me how, though - I don't do Windows).

Well, it worked... but because Windows changed its configuration (now reading the drive it is installed onto (the same one it was on before) as Drive D, and the shared FAT32 partition as C... stick with me, this isn't a Windows question, I promise.

When I installed Ubuntu, Debian automagically added the Debian Linux kernels it could find, which it keeps updated. It also ran a one-time detection of any other operating systems. How can I force that detection to run again?