Thanks for the input chaps.
Regarding the next Top 100, I will just start from scratch and ask everybody to vote again. You are right that the majority probably won't change it but a few might do (people are always discovering games new to them or their tastes might alter slightly) and of course we will have a whole bunch of new members and those who missed the original vote for whatever reason. I think the easiest way is just to get everybody to vote the same way they did before (even if it ends up being a copy and paste job). Inevitably some who voted last year won't vote this year and we could end up with quite a different list which could be interesting.
I'm still thinking about the PD list. Maybe voting for five rather than ten would be a good idea but I'd still be concerned we wouldn't get a great variety of games voted for. I think doing it by genre would make things a bit more complicated, if I do it I'd rather do it as one big list.