I would look at the MS 1400 light and you will still have money to get the taillight as well.. I have been using the MS 900 model for over a year and it is still working well, no issues with the battery, have not really had it in a downpour..
http://www.geomangear.com/index.php?...roducts_id=161
http://www.geomangear.com/index.php?...roducts_id=206