Sure, as long as the amperage rating is at or above what the monitor needs.
Oh, and of course as long as it has the right plug end on it.
http://www.elotouch.com/Products/LCDs/1939L/This is the monitor I bought. Can you tell what amps this pulls from elo's web site?
I have a brick that says "OUTPUT: 12.0vdc 750mA". It was taken from a old router I had laying around.
Looks like the plug is the same but I don't know about the amps. I found that this monitor requires 45 watts???
EDIT: I found out that the plug I need requires 4.16 amps. Hmmm, I guess I need to figure out how mA converts to amps?
EDIT again: 500 mA = 0.5 amps Also, you'd take 45 watts/ 12 volts = 3.9 amps
Guess I answered my own questions but I hope this can help someone else with the same situation.