When I tried to set it up with my HP MediaSmart Server though the HP installer would constantly generate a Windows error, before displaying an error message with “RegOpenKeyExW” and then exiting.

Trying the vanilla installer from a system-builder install of Windows Home Server lead to more helpful information, and a series of steps that will resolve this problem;

For anyone encountering the “RegOpenKeyExW” with the HP MediaSmart Server/Windows Home Server, and Windows 7 try the following steps;

1. Click Start button and type “Command”. When  “Command Prompt” appears in the list, right-click on it and choose “Run as Administrator”
2. Enter the following: reg delete HKLM\SOFTWARE\Microsoft\SQMClient\Windows\DisabledSessions /va /f
3. Press enter. If you receive an error you are probably not running as an administrator.
4. Close the command prompt. The Windows Home Server connector software should now install successfully.

Currently you’re Windows 7 machine will be listed as “Windows Vista”, but that’s a known issue!