Thanks to everyone who put forward suggestions for a system to run Dollhouse in. Savage Worlds and FATE came up more than once, as well as Primetime Adventures and Tri-stat DX. However, I was drawn to Aaron's Dollhouse system, What You Don't Know, that he based on Risus, a nice rules-lite game that offers flexible mechanics that are easy to use. I read over the rulebook he made and I found it to be a pretty good adaptation of the show. It allows for quick character creation for each imprint and includes various rules that make the setting feel true to its source material. It's worth checking out if you want a lite system to run a Dollhouse game. I'll also be checking out the other rules that were suggested by my commenting delvers and see how they weigh up against each other.
So, thanks again.