Personally on my E46 went the BMW TV Module with modified composite (2) inputs for video on my 16:9 NAV display. The picture is good for my carpc (not great but pretty good). For the E83 I bought a G-NET video module. I just sold it on Ebay for about $150. I wasn't impressed with the video quality off of the G-Net module. Initially I bought another BMW TV Module but never purchased the cables and never knew where to install it on the E83 (not really a whole bunch of space in the drivers side compartment with the MKIV, Sirius, BT, etc). The only thing I liked about the G-Net module was its size and plug n play setup. Recently I purchased a new interface. This one has a VGA input and built in IBUS interface. The quality of the picture on the NAV display is excellent. It's priced around 219 Euro (306 USD) which is a pretty good price for what it does. It is bigger than the G-Net module but still easier to place versus the VideoTV tuner module. It is custom made for the BMW where as what I see out there is more generic (like the G-Net) and typically is made for a variety of vehicles. The current challenge is the carpc. I am testing three and leaning towards a mini 6"X6" PC. This PC would fit inside of the side panel next to the Sirius module. The other two (one pictured - VoomII) and another one would have to be relocated. Just recently found another location which would work for the larger footprint PC's.

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E83 - Aero PKG Mods installed: Homelink mirror. CIS-IBUS video module, AUX, Rr Dr Release, stock wheels, Remote start, CarPC (Atom) & mud flaps - NAV - MKIV - NA Map DVD - 2011
E46 - 18.5 wheels/tires (summer), 17 stock (winter), Homelink, NAV software upgrade, BMW video module, Radio to V53, AUX, USB IBUS interface,BMW alarm install, CarPC(Epia), remote starter, tank battery & angel eyes. NAV - MKIII - NA Map CD - High Version 2008.1