Right, rather than spam the thread on the GHII article figured I'd spread the joy here and tell y'all to go download Frets on Fire! I've just wasted about four hours on it and still can't get past medium on most songs. The game only comes with three songs and a frankly hilarious tutorial, but if you check out the Fan Forums here you'll see just how many songs are available for it (including both GH games worth) - they even have the Power Rangers theme song! Go give it a try and you'll never look at a keyboard in the same way again
You probably want this then: http://blog.pcformat.co.uk/page/pcformat?entry=frets_on_fire Would make a good bit-tech project