SME server case study

A real case study:


Background

We are a small Consultancy Company. In our office we
have 6 Windows worksation connected trought a wifi lan
to a 2 adsl line to go on internet.
For website and email we use an external hosting
provider

What we need?

a File server for files archive, a System to
share agenda and calendar and our contacts. Maybe it
will be useful to access to our files remotly and let
external to deposit files in a dedicated space
(something like FTP but secure). basicly these are the
requirements additional features are welcome.

Which solution?

SME server 
or 
A mandrake Server with addon applications


Dear Richard,

If you can whisely advice me I will write down a real
case study to be inserted in our lug website  becouse
I really have to buy a server for my office.