Eithe E-PL1 or E-P2 paired with the Panasonic 20mm f/1.7
You get a fast, sharp prime with image stabilization. Panasonic models lack in-body IS
eh, IS isn't a necessity. My 20/1.7 is fine on the GF1. And the zoom has IS. If the OP wants to use more legacy lenses, then yeah, the IS will be a significant factor because they'll likely be longer lenses and thus even longer effective focal lengths.
A 20 on a G2 or GHx is still pretty compact, and has probably the best EVF implementation for m43s. Not to mention better video (but doesn't seem to be a factor here).
Costwise, GF1+20 kit was recently $600. It hits that ever so often. The 20/1.7 on it's own is ~$330.
But a lot of people favor oly's jpeg processing and it's IS, so the E-PL1 is pretty cheap and IQ wise, virtually the same as the E-P2. And the collapsable lens, which you don't want, can be useful.