Remote Desktop: Win 7 Home Prm can't connect to Win 7 Ultimate

Hi All.

I have a Win 7 Home Premium box along with 4 WinXP boxes in a simple network. My Win 7 box can Remote Desktop to any of the WinXP boxes, and be used to "drive" them, no problem.

I added a new machine yesterday that came with Win 7 Home Premium. After searching through other threads, I found it was stated that if I upgrade the new box to Win 7 Pro or Ultimate, I can then use my original Win 7 Home Prm to connect to, and "drive" the new Win 7 Ult. box.

I successfully upgraded the new box, it's now confirmed to be running Win 7 Ultimate. I have also disabled the firewall, and checked the Remote Box Settings:
Allow connections from computers running any version of Remote Desktop (less secure)..

However, the Home box cannot connect to the Ultimate box. It times out with the following error:
Remote Desktop can't connect to the remote computer for one of these reasons:
1) Remote access to the server is not enabled
2) The remote computer is turned off
3) The remote computer is not available on the network.

All three of these conditions are false.

Please help!!!

Thanks,
Jerry

PS - I can ping the machine, so it's "there" in some form or fashion...