At the moment I'm using roughly 130GB of data per month. I expect the bandwidth to decrease quite a bit though. I've gotten the Swedish University Network to do mirroring of hMailServer (http://ftp.sunet.se/pub/pc/mail/hmailserver/
). This will soon be the primary download location for files older than 24 hours (they mirror once every day).
As for disk space, the VPS I'm currently using is using 12GB. My files are roughly 5GB and the rest is operating system stuff.
Also, since the main purpose is for me to be able to run the latest hMailServer versions, it helps if the VPS can run Windows.
Bill48105, the current VPS was offered to an employee at a hosting company. His hosting company let him run his own VPS'es for free. That has changed which is why I'm moving...