What's lost when I change names, or hard reset?

Question

My first question here:
I've used a Zire 21 for many years, and have some commercial software on it that required activation codes that were e-mailed upon payment.  One is Piloc, a foreign language localization program, the other is SuperMemo, a flash card program for the same. I use them every day.
Now I've bought a Treo 680.  That software isn't compatible with the Treo, so I'd like to keep the Zire going.  But standard installation of the Treo software has the Treo using the old Zire user name.  I'm sure I can't synch my Zire using that same name.
Reading manuals & online info, it looks like I can give my Zire a new user name by a hard reset (scary!), or by a hidden rename procedure involving the shortcut graffiti stroke, a dot, etc.  If I understand it correctly, this will allow me to reinstall software and data (like flash card progress data).
But are my software activation codes likely to work?  Supermemo in particular claimed it calculated my activation code using my user name.  That sounds like it would prevent a reinstallation ... unless the software "knows" that it's been paid for, and allows me to reinstall even if the user name is different.
Does anyone know for sure how this will work?  Will I be able to reinstall?  Would a synchronization then re-load all my progress data on the flash cards?  Should I try a rename (instead of a hard reset) in the hopes that less would be lost?
If there's a high likelihood of losing everything, I'd probably just keep charging the Zire and hope it never crashes!
- Frank Krygowski
Post relates to: Treo 680 (AT&T)

Answer 1

I did a hard reset of the Zire, then went through the digitizer calibration and time zone setting, then synched. 
I get a window popping up that says:
"This Palm Powered [TM] handheld does not have a user account associated with it.  Please creaste or select an existing user account to synch with handheld.  What do you want to do?
[default radio button]  Create a new user account named [blank box]
[alternate radio button]  Select an existing user account  [Choices in this box are Frank Krygowski Treo, and my wife's dead Zire named Peg Krygowski]
I assumed I was supposed to use Frank Krygowski Treo username.  The hotsynch proceeded, and a very long Log file was generated.  But the Zire now has no calendar data (the two handhelds previously had nearly equal calendars), no "to do" lists (which were identical and extensive), no ToDo lists (which were extensive) and so on.  Also, the foreign language software (Piloc and a Polish-English dictionary) are either missing or not functioning.
What gives?  If the backup files are an image of this Zire, I'm afraid I'm in trouble.
I _really_ don't want to lose the volumes of data (to-do lists, calendar, etc etc) that are now only on the Treo.  Is there a chance I should change the Treo's username once more, then re-synch?  Or did I goof in choosing the Treo's username?  Should I redo the hard reset and re-synch the Zire with the original username, "Frank Krygowsk"