Well I have vbulletin in mind. Some others also recomended invision power board. I would like to have some advice on that.
As for daily active users, it would probably be some where around 60-80% of the total users (it's just an estimation, but a good one). If the disk space keeps on increasing every month, is it advisable to start with a heap or get an upgrade as it goes ? also assuming a user makes an average of 3-5 posts per day (for the 60-80% i mentioned) wat would roughly be the bandwidth consumption for a month.
Stromhosts : as you mentioned dedicated, I get the impression that in the case of the number of active users goes above 1000 there would be a drastic change in the forum. Is it practically true for all forums? if yes, is it worth having a dedicated server. wat about VDS ? thanx a lot for your advice.