S B This is a really great suggestion. DeNoise is an incredible product, and it has *just* been made even better with version 4.
It's an enormous improvement on Photoshop's native filters, and is at least the equal of (though typically much better than) its more expensive commercial competition. Its user interface is superb.
Topaz Labs' other plug-ins are really wonderful--perhaps Adjust is its most popular. Even better than DeNoise, though, would be the whole Topaz Labs Plug-In Bundle.