I know this won't be much help but i use PhotoZoom Pro 3 by BenVista (i'm a MAC though they do have a PC ver that runs on XP VISTA WIN7), but it's pricey (i had the company pay for it)...  They also have a "classic" version (a bit cheaper), and both have a "Trial" version (watermarks the file) to see if it will do the job for you...

 

I've really have had great results with it on my photography, but it might be a TEN DOLLAR solution to a TEN CENT problem...

:)
retrocity