Perils of Proprietary Formats
Here's an interesting BBC article on the perils of buying proprietary software that pushes vendor lock-in to absurd proportions. The UK National Archives, in the past, invested lots of money to digitize its documents using Microsoft software.
Imagine saving your digital files in Microsoft Word version 2, which now could not be opened by MS Word 2007. Imagine further that you have upgraded your OS to Vista which will not run MS Word 2.
In fact this is my problem too, since my old articles which were typed in old versions of word processors (circa DOS) are now inaccessible.
The outdated Microsoft file formats used by the UK National Archives are no longer compatible with the latest versions from Microsoft. Users cannot open the files. Since Microsoft insists on closed file formats, the UK National Archives could not even do something about their problem. And Microsoft's workaround has been to provide an emulator (eg, You run an old version of Windows inside Vista. Then you run Word 2).
The quote from Free Software Foundation Europe succinctly sums up the issue:
If Microsoft had used Open Standards from the moment it was founded in 1975, this problem would not exist


digital dark ages
hey benx,
have you read Stewart Brand's "The Clock of the Long Now: Time and Responsibility (Ideas from the world's slowest computer)." He has a section on the "digital dark ages" discussing precisely what you are talking about. (part of the essay is here.)
I refer you also to the Long Now Foundation, especially their Rosetta Project, which is part of the creation of the 10,000 year clock.