Each piece of software should be contained entirely on a card, about the size of a current PCMCIA card.
On my desk I would have a row of slots into which I can insert a number of cards.
If I want to use a Word Processor I grab my Word Processor card and stick it in. Nothing visible should happen. No install screen, no auto-detection dialog box, nothing.
If I want to use the Word Processor, I pull down a list of available application cards and pick the Word Processor.
No installation is required. Any personal configuration changes I make are stored on my Configuration Card.
If a coworker want’s to use my Word Processor I just pull the card out and hand it to her.
If I move to a new machine I have never used before, all I need to do is insert my Configuration Card and it knows what color scheme I like, background wallpaper, position of toolbars, and any other of a billion preferences.
The Configuration Card keeps track not only of system preferences but of individual application preferences.
Each application stores all its preferences in a seperate file so if I stop using an application, or a config file becomes corrupted, I can remove the file from my confiugration card and not affect any other programs.
If I remove an application card before closing the software on it, the system should save an “Emergency Termination Recovery” file that would allow it to gracefully, naturally, recover next time I run the application.
Removing the card should not be a “bad thing” but a normal way to work with the software.