I've been putting actual files on the desktop for years. Try it!
You're using the Comcast cable modem/router/WiFi for wireless? One would think that you would have your own WiFi / router for all your stuff?
Lumia 900 AT&T, running 7.8 OS version 7.10.8858.136. Over the air notification said I had current version. However, hooked up to Zune software and immediately popped up that an Nokia Update...