======= Date Modified 12 Apr 2012 16:55:16 =======
======= Date Modified 12 Apr 2012 16:55:04 =======
As no one seems to have answered I'll give it a shot.
As far as I am aware you will be fine so long as you completely re-word it. This is assuming that the conference piece is a chunk of the larger journal piece. If they are literally the same work (not the conference being just a piece of the journal one) then you should not do the conference thing. This would be what's called "self-plagiarising". If you do not change the wording of the conference piece from the section of the journal piece you will get the same problem.
I am happy to stand corrected on any of this, but this is how I understand the situation.
Hope that helps.
Ninja edit: So basically, in your situation, re write it with different words and you should be fine.