Re: "Personal" computer no more
I was using the The Bat for years until 2010 when I moved entirely to Ubuntu and couldn't use it anymore.
The way I overcame this loss of a decent program, was by using Thunderbird, with a bunch of addons to make it more powerful.
I had tens of thousands of emails in The Bat which I needed to port, so what I did was I set up an IMAP mail server under my control. Made myself an account on it and setup access to it through The Bat. I then dragged (using The Bat UI) all the mail that I wanted to keep, into the IMAP folders (which in my case were actually hosted locally). This got my mail out of The Bat's proprietory storage format and into standard maildir format. I then backed up the IMAP storage location. Reformatted the computer with Ubuntu, setup another local Dovecot IMAP server and restored my backed up IMAP mail to it.
I could then setup Thunderbird, using the local IMAP server as my local folders and that would be where I would archive my mail forever more. This means that I will never be bound by proprietary formats ever again.
That was 5 years ago. Today, I love linux. I could never go back. There is nothing about windows I miss, except perhaps, support of some peripherals, but that's improving all the time. I still print, use webcam with Skype (sorry), scan, connect my mobile and open MS formats. I don't have anivirus software and don't need it. My passwords are stored locally in a KDE Wallet and I'm confident that all is secure.
In short, I can sleep at night. Good luck with your migration. You're in for a treat. :-)