Over the past 15 months, I've bought three different 'software' DVD's from vendors for my SL55 (long story why, won't go into that). I recently bought and installed one that is by far the easiest to install and use of any I'm aware of. I've installed it on my Dell PC with windows 7 OS (it operates on windows XP with a virtual machine), and the installation of everything went extremely smoothly. I then installed it on two Dell D630 laptops (one with 7 OS and one with XP OS). Slower install, of course, but still very straight forward. I particularly like the fact that it allows me to easily print pages using my wireless printer. This seller also sells a set of DVD's with wiring diagrams etc.

The service and parts DVD seems to be essentially a copy of the MB shop manuals etc. I have no connection with the seller other than being extremely satisfied with his product.

http://www.ebay.com/itm/Smart-WIS-ASRA-EPC-EWA-2013-OEM-Service-Shop-Repair-Manual-Set-Combo-Pack-/321638801515?pt=Motors_Manuals_Literature&hash=item4ae32aa06b