It's not that complicated once you've got it figured out, but it can take a lot of time to get it working the first time.

(note: Most of these are Linux-based commands. It's just a fact of life that Linux plays better with others than Windows does — Linux is much more adept at getting lots of different operating systems to boot properly. Also, Windows live-CDs are pitiful, while Linux has a vast ecosystem of rather nice live-CDs: Knoppix, SLAX, etc. It's best to learn these procedures from within a live-CD, because that allows you to get operating systems booting on computers that don't yet have a working OS.)

Commands to set up the MBR

• Linux-oriented bootloaders
  • install-mbr /dev/sda
  • lilo -M /dev/sda
    (note: this is not lilo-specific, it works fine with syslinux, etc)
  
  
• MS-DOS
  • ms-sys --mbr /dev/sda

Packages

• Knoppix
  • ms-sys — available by default
• Ubuntu
  • install-mbr — mbr
  • lilo — lilo
  • ms-sys — not available from official repos, because it contains a verbatim copy of Microsoft's boot block
    • instead, download from ms-sys.sf.net and compile
• Debian
  • install-mbr — mbr
  • ms-sys — removed for copyright reasons; download from ms-sys.sf.net and compile