My sister has the 27-inch 2.66GHz quad core.
It is certainly a big screen...
But!
Aside from the fact that is a mac (which I don't care for) it's is very limited due to it's hardware, because it essentially uses laptop parts to be that flat. I have a 27 inch monitor and a big clunky tower but when my computer starts to age I can upgrade, she cannot (she already maxed out the ram, it uses laptop ram so don't hope for a big boost there).