Concurrent RDP on windows, legally

[epicfail]

Anybody know what versions of windows will allow concurrent RDP to allow multiple user log in to one system, i know you can install a patch or edit registry but i need to stay within the terms and conditions of ms.

Thanks in advance for any suggestions

 

[carnageX]

Configure the Number of Simultaneous Remote Connections Allowed for a Connection

Not really sure how installing a patch would be illegal...
Enable Concurrent Remote Desktop Sessions in Windows with This Patch

 

[marry_smith]

Window7 or window XP that will allow concurrent RDP to allow multiple user log in to one system.