Yes, I use both reviews and "chatter" on the boards to influence my decision. (Incredibly low prices on E-Bay don't hurt, either...I'm likely to take a chance on a product that I'm not too sure about if it costs under $5..!)
There are certain companies that are usually reliable (Fantasy Flight, Green Ronin, others) and if I'm even slightly wavering, a positive comment will influence me to purchase. (I discovered Midnight and Mutants & Masterminds this way--thank you, folks!) Sharn is the most recent influence in this vein.
Then there are companies that, despite glowing comments, I have to wait to see many positive reviews before I'll even think about buying one of their products (Mongoose and their horrendous editing immediately come to mind....Bab5 [the first hardcover] was poor, but Conan [pre-Atlantean version] burned my butt hard and was kind of a final straw for me...had I waited a few more months and overcome the hysteria/hype being generated about those books I'd never have purchased either). The reviews of these products have got to be consistantly outstanding--whether 'official' review or just chat on the boards--for it to win me over.