Well, since you brought it up, you can use RDP from any computer that has Internet access to connect to another computer XP or WIN 7 with RDP availability.
It would be easier if you gave the model numbers of the ActionTek and Cisco, but I'll try anyway. A modem can double as a router and can be used many times in home setups to provide a connection to the Internet even without a router. In your setup, it sounds like your ActionTek is your modem. I would definitely connect it to your Cisco router/firewall and let the Cisco be the default gateway. The Cisco router would then connect to the switch along with the clients and server.
Once you are using the SBS setup, you will no longer need to port forward for RDC connection. That's part of the advantage.
One other thing. And, Sandeep and I were both adamant about the DHCP on the server. It has always been that way and is on Standard. But, here is a quote from my networking guy:
I can appreciate it goes against everything you have learned, and I have professed, but it is 100% correct. SBS essentials is no more like SBS standard than a hot dog is like a hamburger. Most ITpros like myself do move DHCP from the router to the server, which is quite acceptable, but it is not the way SBS essentials was designed.
