I got the update info when I opened up the application. After reading through all the warnings about doing a full uninstall/reinstall I did a backup, downloaded the new version and installed it. Unfortunately all I get now is a message box, "BigOven expects a newer version of Windows. Get a newer version of Windows."
I'm not terribly surprised that it no longer supports a 16-bit OS. BUT, I'm a bit surprised that the upgrade info didn't warn me about it. I would have updated the version on my (WinXP) laptop and left the older version on my (P3, 900mhz) desktop.
Of course this is an incentive to get off my butt, get out my wallet, and upgrade my desktop machine. I just wasn't quite ready to do it this weekend.