I'm not sure what your term means: "It worked before I got it" - that's a pretty confusing statement.
How do you know it worked?.... before you got it, how could you tell?
And monitors have a VGA interface, not a Parallel interface as stated. I certainly hope that you haven't connected it to a parallel port. I don't think that's possible though.
Mag doesn't list this model: http://www.maginnovision.com/Support/Downloads.aspx
In Device Manager, under Monitors, if it states: "Plug & Play" (as you stated) then it doesn't need a driver installed.... Windows XP is providing the needed support. It sounds like you have a monitor problem or a video adapter driver problem. I'd test it on another pc to make sure.