Proper network configuration.

I inherited my network.
I want to redesign it, properly.
I have 25 users on the network.
I have an Internet connection and Firewall.
I am using exchange 5.0 right now.
I have a web site using IIs 3.0 right now.
I have files and printers to share.
I want users to be able to remotely access
email, files and printers when out of the office, through RAS and the Internet.
I am looking for a simple diagram on how
this network should look.
Does anybody know where I might be able
to find network diagrams?
Or could anybody draw up a quick diagram
of how my network should properly look?