OK , it' s probably less dificult than you think.

First, look over the many caveats abou installing Knoppix to HD that abound in these forums. If you have others like Ubuntu etc. try them out as live cd's and see how you like the look and feel. Since you already have some cds burned go ahead and install them to hd and see if they seem to work ok.

There are a bunch of IMAP applications that can be added via whichever distro you end up installing to hd. Adding the app doesn't mean downloading the entire distro cd, just the app. Probably not alot of time even on a slow connection.

The package manager that comes with Knoppix is Kpackage, for Ubuntu it's Synaptic. To take a look at kpackage for the knoppix live cd click on K->system->kpackage and search for packages containing the keywords for the app (file->find package)

good luck