Easy Solutions.
I have been developing and selling Excel-based scientific data analysis
software since Excel 95. I initially shipped my software in Excel 97. Excel
2002 introduced bogus format error dialog boxes upon opening the Excel 97
template so I converted the software to an Excel 2002 format. Now I ship two
versions (97 and 2002) with every order to cover the span of six possible
versions (95-2007) users may be running.

Update Headaches!
It is time to update my main software to add some new code and statistical
functions and other features. As an aside, I had to do a project for a client
running Excel 2002. In the process I noticed how this version manages
worksheet control properties differently from other versions. Good thing I
have books on all versions to date. But what a chore to research the impact
of MS' endless fiddling as illustrated by the topics in this forum. I
mentioned that an an example of the type of problems I now expect to face if
I proceed to update and modify by standard software. Am I faced with making 5
versions to accomdate the endless MS changes? Will users of my software find
it impossible to share workbooks across different versions? Will I have to
dumb down new features to fit Excel 97? Will I have to dig up my old Excel 97
(shipped as a set of 3.5" floppy disks) and install it on a cheap computer to
make my update with? I've got 7 computers in mothballs, enough to test all
Microsoft's ingenious version progression. But will a 1995 Dell still work?
And 7% of my sales are to Mac Office users.

If you see my dilema, Excel version hell is giving me second thoughts about
improving and upgrading my main Excel software program which is used in 67
countries at last pivot.

Better Solutions?
So my questions is: What solutions/suggestions/resources can you offer
regarding keeping Excel software updated and deployable within the mass of
versions available? Surely others face this problem perpetually (for example
J-Walk with PUP, ASAP Utilities, and the wide world of Excel MPV's and other
Excel product developers.

Any suggestion would be welcome. Some things I have consdered are running
all versions of Excel on one computer for development and testing. Find out
if Excel 2007 allows for a broader range of saving *xtl files in older
versions. Dumming down new features to maintain identical copies available in
97 and 2002 versions only (forever).

Watch for FallingRock and thanks in advance.

(Although Gates can resell his products through endless version upgrades, I
can't.)