I have an early 2008 iMac A1224 (EMC 2210) that I want to use as a monitor for an Apple laptop and, if possible, a PC laptop. Is this possible? How do I set this up? Any pages dedicated to step
by step instructions would be appreciated.
iMac Line (2012 and Later)
Not possible.
What you are describing was called Target Display mode, unfortunately 2008 iMacs did not have the hardware to support that. Apple has since dropped TDM and it's support for other iMacs. If you are interested you can read Target Display Mode FAQ.
My suggestion is to simply buy an external display for the laptop and PC.
How to use old iMac as monitor
