Time Delay Shutoff Relay

First off, im an electronics noob, so be nice :).

I'm trying to make a relay that shuts down the circuit about a minute after the ignition switch it turned off.  I was thinking about using capacitors to delay the shutoff, but idk if that will work.

I'm setting up a computer in a car, and want time for the computer to shutdown after the ignition is turned off.  I have a SPST relay attached to the power switch of an inverter that closes the switch when the ignition is on.  My relay is a SPST 1 amp.

a minute is a long time for capacitor delays, you will probably want something solid state.

I've had suggestions of a "555 Timer" and  transistor thing?  Here are links to similer setups:

http://www.astron.nl/~smirnov/poweroff.html

http://www.kpsec.freeuk.com/projects/timer.htm