I've two monitors that have higher resolution: one is dell (29'') and the other once is the HP ZR2740w (27'').
When I connect the monitors to the laptop displayport connector they are not recognized (they don't even show as a device in the hardware devices). Any monitor of 24'' it is recognized automatically recognized. I think that anything bigger & with more resolution won't work.
It's a little bit disappointing given both monitors are expensive and where working with an old SNB Lenovo laptop.