A few years ago I rolled with 2 monitors but I found it quite problematic. Nothing really has "real" support for duel monitors. For example when playing an MMO I believe you should have the game running full screen on the left screen and the right screen taken by all the UI elements that normally block your view (maps could be HUUGE) but this doesn't happen.
The only benefit is so you can have websites or chat programs open at the same time but now I used a laptop for that and my PC power is entirely dedicated to the game instead of trying to display two monitors.
I think a PC and a Laptop is the better option than 2 monitors.