God's Box
This box (naughty name but memorable) contains the important bits you or your guru will need when your computer fails.
It should be kept on the top of the wardrobe - safe, not too easy to get at, always up to date and complete.
This is the ideal list which you should do your very best to keep complete:
A book with all the settings of your motherboard CMOS written down. Also all your IDs and passwords accurately recorded - be fussy about upper and lower case characters and keep this list up-to-date - you may also keep internet banking passwords here if you choose. Any special computer related information - settings, product suppliers, phone contacts, etc
Perhaps you could keep all the paperwork for the computer bits here.
Motherboard driver disc
Video card driver - sometimes included on or with the motherboard disc
Monitor driver disc if needed
Modem driver disc if needed - dialup, ADSL or cable
Keyboard and mouse driver disc if needed
Printer install discs
Scanner install discs
Digital camera discs if needed
Drivers on discs for any other bits attached to the computer
All manuals to do with the above bits.
Operating system disc - Windows XP or whatever - see Installing XP
It follows that you should also have another box containing all your other stuff, accessories, software and manuals etc.