Our office had this old school windows 2003 domain setup, our server caught fire, and now we are looking to do it right from scratch.

Here is what we need: 5 PC and 3 Mac workstations for web development, they will each have WAMP/MAMP setup on them, managed by their developers. We will have a file server for assets, and a LAMP server with an external IP for staging.

Here is what we have to work with: 5 IP addresses, brand new PC file server with windows 2008 SE, D-Link DSS-16+ 16 port switch, belkin 5 port wireless router, cable modem with 4 ports.

How I have it set up now (this is a temporary makeshift setup):
Cable modem => LAMP server, wireless router
Wireless router => Switch => All of the workstations and file server (setup as a workgroup).

We have noticed our internet is very slow with us all plugged in to the switch, and the switch plugged in to the router. I am not positive, but I think it is because our router does not have NAT. We are also having problems with the MACs connection to the network drive - it keeps disconnecting.

I want this done right, and we have a ~$600 budget to buy anything else we need. Does anybody have any advice for me? Should I set up a domain or workgroup?