I second the comment on reading Mike Focke's page. I thought I had it goin' on with my own pages until I saw what he's put together. It's brillaint!
Drive a bunch of them and be very very picky. There's a bunch for sale and the prices on used boxsters are set at sublime and ridiculous levels and everything in between. There's no rhyme or rhythm for it as far as I can tell.
You will never regret buying the newest, lowest mileage S you can find. The larger engine and the glass rear window in the 03's and up makes all the difference in the world, I assure you.