I'm a big fan of this one at work: http://www.amazon.com/CoolGear%C2%AE-Serial-Adapter-Prolific-Pl-2303HX/dp/B00H8VN6FA

The benefit is that between a standard Cisco blue cable and that cable, you get about 12 feet of throw to go around or through racks, connect to an AP on the ceiling, etc. It's bulletproof on Win7, so I don't think it's a knockoff Prolific.