We've got a bunch of OptiPlex GX270s around here [albeit the tower models] and they are great computers, with the exception of the annoying design of the flap that covers the usb ports. Most of them have been removed on the machines in our office.

The student lab in the same building now uses OptiPlex GX520 and OptiPlex 745 machines, which have a newer enclosure that has done away with the flap, which is nice.