We're using D&D 3rd Edition, but there are a few rules that we have extended/changed:
If you roll a one on any roll for hit points, you get to reroll it.
(Note: the balancer on that is I use the same formula for determining NPC/monster hps)
We will try and maintain that we will play once a month, although preferedly more than that. I will try and arrange a bi-weekly time that suits everyone, however if players have to be gone, I will NPC them with the promise that they won't die unless everyone in the party dies, and you only get a 1/2 share of experience for the session. If half the group cannot attend, the session will be rescheduled.