true dual monitor rdp connection on windows 7

"Very, very after the fact, but I saw this had never been answered...

The functionality you're looking for (which normally just requires checking the 'Use all monitors' box) ONLY works if the target machine is running Windows 7 Ultimate or Enterprise (or Windows Server 2008 R2). This is one of the few legitimate differences between Professional and Ultimate.

Note that it doesn't matter what version is on the machine used to manage the remote session, only the target machine (although it needs to be new enough to support this, I think Vista and higher.)"