I have seen several references to Neat having been used to help with "noise", "moire" or just plain sharpening.

If if purchase the product, what can I realistically expect?

Download the demo and try it http://www.neatimage.com/

You might also want to try Noise Ninja http://www.picturecode.com/download.htm

Also give Imagenomic's Noiseware a try. An excellent piece of software.

http://www.imagenomic.com/

Chris