Windows 2000/Network architecture...

I want to get some different ideas on how best to configure my current network. I have 10 WAN locations, but all locations are within 5 miles of each other. Most locations have 1-2 nodes. 1 location has 25, 1 has 15. Our central office houses 80% of our employees (has a fiber backbone). All are connected via high speed wireless (256kb-756+kb) and are behind firewalls. Currently, all 250 PC's (NT and 2000 boxes) are in a Workgroup...however I am setting up two 2000 servers at our central office. One is already setup as a DC(1.3 gig processor with 1 gb memory). I also have a server with dual 1gb processors and a gig memory. I wish to use this (dual processor)box as an Exchange server and another DC. Both are in a test environment at present. My goal is to create one single domain, but I would like some feedback on how to go about this. Obviously, the amount of WANS and differing subnets create some complications. I am an NT guy and am a rookie on 2000. We are working on a very limited budget...so please keep this in mind. Obviously, it would be nice to create 11 sites with DC's in all...but 6 of the sites have 1 pc/1 printer. Presently, all sites come thru our central office for firewall VPN authentication. Basically, we are a Hub and Spoke architecture. Netbios is turned off. The remotes do not need to see each other. They only need to communicate to the central office (that holds 80% of the employees). I have created my domain. I have setup AD and DNS. I would like to know more on adding remote WANS to the domain. Bandwidth has not been a problem. There is not a lot of file sharing. Extremely light users on network. **Advantages and disadvantages? Thoughts and advice? Any advice or suggestions or instructions would be extremely helpful. I am still reading MS Press books on Win2000...so I am not at all an expert. Thanks again!!