You need to have installed the 64 bit version of zaepg for it to work, as far as I know the the MCEGuide installed doesn't cater for 64 bit as the registry key would be written into the 32 bit registry emulator.
As explained in other posts, zaepg's only role is to maintain that one registry key, and it does that by running a windows service application (Control Panel / Administrative Tools / Services) that monitors it. Zaepg no longer provides guide data, it just points to the mceguide info, which is why you need to register with MCEGuide.
It seems like you have it installed correctly now if you can see that registry value. After that you would need to restart the windows media center application and run the guide setup from the settings. After the wizard has completed, media center uses that url from the registry and a value that identifies which guide you selected (called a headendid) to download the guide on a daily schedule. From what I can see, the urls that are there are working, is it possible that you selected a guide in the past and that guide's headendid is no longer available?