These have all needed a fair bit of PP and are still dark, but at ISO800 they can't really be brightened up without a feck load of noise (and I've reduced a lot of noise!)...
Like you say, a shame that they are dark, but I guess a tripod wouldn't be much use in this type of situation; doesn't look like you could have gone much wider with the aperture either. I like that it's not obvious that they've had a lot of PP done to them though, quite a hard thing to achieve.
I've heard a few people rave on about a program called Noise Ninja, I don't know if you'd be able to acquire that?