Black screen after freezing when playing Civilization

Hi,

My son has been playing Civilization game on our old iMac and it has been freezing regulary. He always managed to quit with alt=cmd=esc, but yesterday didint work as previously, so I have powered down the iMac and when restarted, the chimes came on, but black screen. It sounds like the computer is on, although I cant here the chirning of the fan? which has been louder for the past few months.

I have tried unpluging and turning it back on. It ejects the CD fine. I even booted with Restore CD +C, but then didint see anything on the black screen.

I have MacbookPro too, some sugestions of connecting it as a second monitor, but could find what cables/connections I need from the ones I have.

Thank you

Pavlina