Cloning a Partion in dmg to HDD

During my computer repair, an Apple Genius copied my linux (ubuntu, latest) into a dmg, threw it on an external hard drive, and then reinstalled 10.6.5. I now have the dmg sitting on my Desktop but it cannot be opened with anything. I have 50 gb's of data that I need pulled out of there but I cannot find any way to do so. Any suggestions?


Someone mentioned using CopyCatX to image Windows partition, so maybe - for future needs - and always something you want to do before disaster strikes.
CopyCatX is device and file system independent application, which means that the user can create disk images from any normal Mac OS hard drive, Windows or Linux device. It can also recover data from a faulty device or scratched CD, and almost any other media or file system that can be recognized in Mac OS X.
Paragon Software has linux ExtFS driver.
Maybe between the two something can be done if it isn't too late of course