Network and Computer infrastructure design

Hi,

I am designing a computer and network infrastructure for our manufacturing company.

We already have a domain name registered and website is currently hosted at the webhosting service provider. We have a software developed in 90s that we are using on our current Novell servers. This will be replaced with a new software developed on .Net platform/SQL server.

Our goal is to design and develop our company's computer infrastrucutre that supports

1. Email send/receive for employees.
We are thinking of using exchange server.

2. Fax sending and receiving using computers from any work station.

3. Remote login to our network using and accessing the new/old software.
We are thinking of using VPN.

I was looking into Dell Power Edge servers with windows Small Business Server R2.
My approach was to have two computers.
1. Web Server.
2. Datbase Server.

Webserver will be directly connected to the internert and it will be the only computer visible from outside. It will also run the exchange server, VPN server and fax server.

I was thinking to have two computer solution to reduce the security risks. So I would like to run minimum software on Webserver and rest of the software on Database server.
How can I keep all the user login information, email data, fax data on the internal server and still keep the website on the webserver?

Also, thinking to configure my Wireless Access Point in DMZ mode to webserver? How this would work when I have a static IP from my service provider?

Any thoughts?
Thanks for your help.
David.