Is it the same display? I was hoping to buy a thunderbolt display but figured if they're the same display I can still connect my MBP to an iMac and just get a new iMac for the kids. Kinda two birds one stone.
The iMac is a good deal. The Macmall closeout on the 27" i7 with mini-Displayport input is a great deal that give you a Mac and a great external monitor for any display port capable PC or Mac for $500 more than the display alone.
Of course the 27" display includes the TB hub and extra ports so there's that extra functionality to consider during your comparison.