Link to Original Source
Mono Squeezed Into Debian Default Installation
And for those like me who were quite excited with the new licensing and wanted to use it with java... Don't think of it...
Qt Jambi - a port of Qt to the Java programming language - has been discontinued in order to focus resources on the Qt cross platform application and UI framework. Qt Jambi will be maintained for one year after the March 2009 release of Qt Jambi 4.5.0_01, and will be made available upon release under the LGPL license
If you consider your data worth it, have enough time and enough money, you should probably re-burn/re-save them to long lasting media.
There was a previous post on askslashdot about this subject.
My suggestion was to use Plasmon "Century-Disc"
(even though I have never tried it myself)