Dual core 2.4ghz? maybe.
4gigs ram? maybe.
512 megs nvidia? what? that tells me nothing.
you need to also set your fps, resolutions, etc.
a third instance of wow would be taxing it.

what you might want to do is make a trial account and use it as a third. check how well all three works with follow, spell casting, trading, quest gathering, looting, and most importantly, switching between the three screens. if all those tihngs are ok to your liking... then sure, it works. if not, you might want to adjust some of the settings.