Looks good Allen...Just one thing...

 Code:
        if $Objxmldoc.getelementsbytagname("em:maxVersion").item($i-1).text<>$FirefoxVersion
          $Objxmldoc.getelementsbytagname("em:maxVersion").item($i-1).text=$FirefoxVersion

Should maybe be...?
 Code:
        if $Objxmldoc.getelementsbytagname("em:maxVersion").item($i-1).text<>$Version
          $Objxmldoc.getelementsbytagname("em:maxVersion").item($i-1).text=$Version

Didn't see the $version parameter in the UDF called on anywehre.