Snow Leopard Server or OS X Server on an older Mac Mini for small business?

My wife and I both work from home and for a while now I've been wanting to set up a server on which (amongst other things) we can host our websites, mail, centrally store files and access remotely (via laptop and iPad) when we are dealing with clients elsewhere around town.

I've acquired a 2010 Mac Mini with the original OSX10.6 (Snow Leopard) install disk. Both my wife and I are using 10.6 on our laptops already, so we are very familiar with it.

So to set the Mac Mini up as a server, should I find a copy of Snow Leopard Server, or is it possible (or perhaps better) to install OS X Server on the existing Snow Leopard already installed on the Mac Mini?