Frankly very tired of all the shouty nonsense rock on Guitar Hero III (really, it should have just consisted of Paint It Black 32 times over), I began to crave other musical delights for my ruined hands. I don't know why I didn't think of looking for this before. Frets on Fire isn't bound by such tiresome conventions as rock songs and guitars. If it's a song, you can play it on your little plastic guitar (or keyboard or gamepad or Strategic Commander) - regardless of whether there's actually much guitar in it. And hence I found myself merrily playing these two fine pieces of Valve-related music...
That's more like it. Though clearly practice is required. In my defence, I will say that FRAPS churning away in the background and chewing up the framerate complicates matters somewhat, but then that's a bit like claiming the only reason your genitals look so tiny is because it's very cold in here.
Want to try it yourself? Filefront are hosting a user-made pack containing both of 'em here. So it's their fault if it's completely illegal, not ours. But if this link is quietly edited out soon, it's probably because I've been killed.
If you don't already have Frets On Fire, then a) shame on you and b) it's here.