First, I have no knowledge of the PDA version(s) of Excel.
However, if you are getting a macro warning when opening the file in XP, it is because there is some Visual Basic module lurking in the file. The module can contain macros, but even if the module is empty its mere existence will give this warning when opening the file.
To remove the warnings, you need to remove the module(s) as follows:
Caution: Removing VB modules may remove some functionality from the file. It may be specific to the iPaQ - I don't know... but I might suggest you work on a COPY of the file first.
Use <Alt-F11> to open the visual basic editor.
Use <Ctrl-R> to open the Project Browser in the editor window.
Look for any folders in the Project Browser other than the folder called "Microsoft Excel Objects" (which contains your worksheets).
The culprit will probably be called the Module folder.
Expand the folder and select any module within it. Right click on each module and select "remove module(x)" from the drop down menu.
Repeat until all the modules are deleted and the containing folder should disappear also.
If you're curious, you can right click on each module and examine the code to see what information it contains before deleting it.
Once you've removed all the modules, quit the
VB editor and return to the spreadsheet.
Save the spreadsheet.
Now, when you re-open the spreadsheet, it should launch without those troublesome warnings.
Regards