On Fri, 23 Sep 2011 05:21:45 -0700 (PDT), Steve Lewis
wrote:

I have now read several threads on various web sites saying that it is
ok to use salt softened water.

Which is correct?

Both. Softened water contains very small amounts of Sodium Chloride
(salt) and some boiler manufacturers were concerned about corrosion
especially with aluminium heat exchangers. Other boiler manufacturers
seem to be happy with ion exchange water softeners so the only
conclusive answer will come from the manufacturer of the boiler you
intend to fit.