What about asking a new user or guest their version number when they first sign in, and if it's not a legit version they can't use the forums. Should be simple enough to do.
Windows XP SP3 Intel Dual Core CPU: E5200 @ 2.5GHz 4.00GB DDR3 Ram ASUS P5G41T-M LX PCIE x16 GeForce GTS 450 1Gb SB Audigy 4 Spyware Doctor with AntiVirus
