You would want the Noise Reduction plug in. http://www.sonycreativesoftware.com/noisereduction
It's not cheap because it is professional software that radio stations, studios, etc use.
EDIT: I see if you buy Sound Forge Pro (not Sound Forge Audio) it comes with it....
In addition to Sound Forge Pro 10 software, this comprehensive audio production suite includes the Noise Reduction 2 plug-ins to fix common audio problems such as tape hiss, camera hum, clicks, and pops, powerful Spectrum Analysis tools for analyzing audio, and the Mastering Effects Bundle 2 powered by iZotope™, a collection of six professional audio plug-ins. Sound Forge Pro 10 software also includes integrated disc-at-once (DAO) CD mastering for producing Red Book audio CDs.