Ah thx! I also have a Windows partition and did try out.
IsoBuster is awesome, it can read all types of proprietary ISOs I had (Nero/WinOnCD) and the raw Linux ISOs! But I couldn't figure out how to convert a full ISO into another format. Extracting and viewing single files does really work perfect.
Then I tried Undisker, which couldn't read any of my proprietary ISOs, only the raw Linux ISOs.
Hmm any idea to convert a full ISO?