This question has been asked many times and was once again asked today on an internal forum. It is hard to come up with an explicit answer, but I feel I can give you some (personal, non-binding, your mileage may vary, please take with a pinch of salt and don’t sue me) opinions. For SBS 2003 the non-scientific sizing appeared to go like this: “between 2 & 4GB of RAM, depending on number of users”. I often saw a machine for around 25 users with 4GB of RAM and there was headroom. Disk – don’t buy 1.5TB disks, but don’t by 30GB either. Buy largish and try to size data before you make the decision 1 CPU or 2, or perhaps more importantly, a box that can take 1 CPU or 2? The the time SBS 2008 arrived the difference in cost of a 2GB or 4GB box was trivial. Now SBS 2008, if you want to be scientific about it would look something like this: Minimum specs are found at http://www.microsoft.com/sbs/en/us/system-requirements.aspx Think Windows Server 2008 for x users, plus Exchange sizing for...