I think I got the pinouts from somewhere else, but this site has a nice schematic of the parallel port pins for your reference.
Mine goes something like this:
Parallel Port AVR Function Color2 MOSI Orange/Grey11 MISO Orange1 SCK Green16 RESET Brown18 GND Brown/Grey
Only tricky bit here: Note that pin 1 (SCK) is on the upper-right hand side when you are looking at the solder pins from the back. It's upper-left when you're looking at it here, and in the circuit diagram.
Also, the guy's website above has ground connected to 20 and 21 while mine (and others) use 18. Many of the pins connect to ground, and it doesn't matter which of them you pick, as long as you get ground.
If you look around the web, you'll find that most people put resistors in either the cable or the cradle (next step) to protect their computer's parallel port from excessive voltages on the AVR chip for use when programming it in-circuit. We will be using strictly 5v here, so there's no such worry, and I leave them out for simplicity.
However, if your chip ever comes near >5v, DO NOT USE THIS CABLE WITHOUT RESISTORS! A computer with a burnt-out parallel port is no fun. That said, I've been using it without incident for 6 months now.