Rockville Community Nursery School
http://www.RCNSCoop.org and Rockville Nursery School and Kindergarten
http://www.rnsandk.com are two different schools- very different schools, actually, in everything from school hours to parent involvement. But close neighbors, both just off 270 at Rte 28.
My 4yo goes to RCNS (the coop school). Last I heard there was room in the 2s (though it's not my child's class so I'm not sure if that's still true). You should call them to see if there is room for your two twos. Good luck finding a great match for your family, and welcome to the area!