Jon,
After installing the Windows Server Inventory Add-on, you should see three new .ConfigMgmtInventory files in the \SolarWinds\Configuration Management\Inventory folder:
50-Windows-Services.ConfigMgmtInventory
51-Windows-Software.ConfigMgmtInventory
52-Windows-Accounts.ConfigMgmtInventory
If you do not see these files, reinstall the add-on package.
If these files do exist, restart Cirrus and then select Inventory Settings from the Inventory menu. You should see a list of Inventory options including the default groups "Standard" and "Cisco". In addition to those groups, there should be a new group called "Windows" with three Inventory options to choose from.
If you still do not see these Inventory options, did you install Cirrus in the default location? And if not, did you install the add-on to the same \SolarWinds folder that Cirrus was installed to? The fastest way to check would be to do a search for folders named "SolarWinds". If you see more than one instance, this is likely the cause of the problem.
If none of this resolves your issue, feel free to email me at ryan.jett@solarwinds.net
Ryan Jett
SolarWinds.Net
918-307-8100