How it started: A real requirement for a Multi-User RDP Windows Hack

Once upon a time ... ... I was confronted with an interesting and (at that time) challenging task: A medium-sized retail chain with 150 branch offices has decided to migrate 150 branch office servers from Linux to Windows. Each branch office had at least two (or up to a maximum of five) thin clients (Neoware/HP/Wyse). The local servers hosted the merchandise management system/database, provided the associated GUI via X11 to the thin clients and had many, other tasks like printing services, access control and work time tracking, etc. These Linux servers actually were just standard office PCs with software RAID and most of them equipped with four GB of RAM. However, the overall system was designed to work without any network connection to the headquarters. A  VPN with  really low bandwidth  was in place for remote management, database backup/synchronization and software update tasks, running during night hours. Now the new requirements for the servers were simple (at least from their CTO