For critical work you really need one of the paid programs.. recommend either Neat Image or Noise Ninja.. If I remember correctly the evaluation copy of Neat Image will not allow you to save a full res copy.. I use Noise Ninja here but as usual with these programs, they take a bit of learning..
Yeah but.. it will only let you save a highly compressed version, ok for the web I suppose but for high quality output not quite the real deal. Nobody would buy the full version otherwise.. except me maybe
I try and avoid noise progy's as much as possible and if I have to, I use Neat Image.
I just hate the plastic look they all give astro images if they're over-used.
If anything try Noise Ninja, I've read it's the best but I've yet to try it.