pdf995 requires Program Compatibility Assistant on Windows 7
I had a Windows 7 computer where I had installed PDF995, but found that it didn't show up in the list of printers. Then I found this - which said that you need to make sure the Program Compatibility Assistant service is started. In this case, the PCA was set to manual - but it was not started. I started it - uninstalled PDF995 and reinstalled it and voila - it worked. Weird.