You could use a Powerflash (PSC01). Set the input to A and the Mode to 3. Connect to screw terminals to an unused +12v (yellow) -12v (black) and out on your PC's power supply. Then you just need to set the light and the power flash to the same code. Remmember you can't plug the PSC01 into your power strip.

Powerflash:

[Link: homeautomationnet.com]