This is one of those it-just-works piece of software. It’s a port forwarder for windows. No installation. Easy to use. And it works.
UPDATE: first, the link to the software: http://www.brooksyounce.com/soft/spf.htm
UPDATE2: The site of this guy, Brooks, is interesting. Especially after reading about the software and then to see this guy’s pictures. The site: http://www.brooksyounce.com/