"The Killing Zone - How and Why Pilots die" has some interesting stats on GA. If I remember rightly the author comes to the conclusion that flying fixed wing GA works out at about the same risk as driving.
Its interesting to note that statistically a GA pilot who gets the PPL and then ceases to train for further ratings or courses but carries on flying is more likely to end up in trouble than someone who keeps training for further ratings. i.e. two 500 hour pilots, one a basic PPL holder, and one a PPL/IR (or aero's course, or IMC, or CPL etc) holder the PPL/IR holder is statistically less likely to be killed. A situation that is not helped by ridiculous JAA training requirements which actually hinder safety from a PPL point of view.
Don't ask me to reproduce the stats, they're somewhere on the web but haven't got time to find them at the mo. Sounds reasonable though.....