camwest,
We have to use an entity for the ampersand or we would not be sending well formed xml. The ampersand is a predefined entity and has to be escaped.
That said, it is up to the feed reader to recognize it and and then parse it correctly. A lot of them are capable of that, unfortunately Firefox apparently does not fall among them. An alternative might be to replace it with a regular ‘and’ using one of the find-and-replace plugins.
Does that help?