Mac Users, this is how I burned the nav os cd:

1) change the mdf to iso
2) in Toast, under the Utilities menu, select Mount Disc Image and choose the "bmw v26 software.iso" file.
This creates a disc image on your desktop called "NAV_SW" with 54 items contained within it.
3) Go back to Toast and select the Copy icon (from Data/Audio/Copy/Other)
4) Go to the pull down menu next to "Image File" and select the nav software (you should see the cd icon and "NAV_SW" pop up
5) Click Record
6) select your speed, click Write Disc and Voila! Works like a charm. Good luck...

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2005 X5 4.4i with SP, PP, CW, RC, Prem Sound, DVD Nav, Comfort Seats, Style 87 Wheels, Alum Running Boards, Sirius Sat, 6-cd Changer.