If the remote computers are running windows XP, look into the NLA mentioned by PeterH. In general, look into 'SSO' (Single Sign On, or Single Session Sign On).
I am testing it right now for my RemoteApp users. I recommend making the Registry changes to a 'vanilla' XP install (I used a virtual machine initially) - export each of the settings, then combine them into a single Registry file. Once done you can easily run the .reg file either manually or via a script onto the computers.
As a note, SP3 does need to be installed which will take care of the RDP 6.1 item as well.