If they don't save the workbook then I also don't need the filename, so
that is ok.
Initially I wanted to have the filename registered the first time they
save it (even if they don't close the spreadsheet), but I guess it's
good enough if I update the filename once they close it.

The reason I don't like the GetSaveAsFilename approach is that this
macro should work for different excel versions, without really limiting
the users, and it gets a big complicated when I also have to figure out
what file types all the Excel versions support.

Thanks a lot for the help guys