I have to agree that forums are an EXCELLENT way of promoting yourself.

Forums do not only sing praise about your products/services (that is of course if they are good) but they also show your potential customers that you have NOTHING to hide. Just seeing that a website has a forum section can ease the doubt that many potential customers may have.

I fully agree with Brad and Eric, put more energy into your products/services rather than using your energy to attack a competitor.