Staying dry is a losing battle, don't beleive deodorant marketing.

My best setup so far: Gore Tex Arc't'ryx jacket. It keeps light rain off but gets sweat *out*. When its pouring the rain goes through the jacket; it gets soaked. *BUT* that's the weird thing; there is a kind of equilibrium that happens and you do not get that wet afterall. And at bike speeds it ends-up drying crazy fast, so if the rain stops the jacket dries in no time and continues to pull the sweat out. Its awesome.

You cannot stay dry but you can manage it