The guys at theDigitalMediaZone explain how to save a little money if you’re thinking of using Windows 7 Pro version just to get the Remote Desktop Protocol (RDP) for your HTPC. Instead they recommend using Microsoft Live Mesh.
Read the entire article on the DMZ and let me know in the comments if you think Live Mesh is sufficient to replace RDP. I personally use LogMeIn for this sort of thing, but I also am testing Live Mesh for another purpose which is a very nice program that I agree you should check out.