You don't need the i-pod. I've got the Nike+ Sportband, basically a wristwatch which is paired with a chip you put in the sole of Nike+ compatible trainers. Having said that, you can buy little pouches for the chips to attach them to the laces of other trainers. The Sportband kit is usually available for £30-40.
It's a pain in the tits to calibrate, and not the most accurate (it clocked my marathon distance at 28+ miles), however as pretty much a running beginner, on the whole it's been pretty decent. You can also create an account on the NikeRunning website which allows you to set goals, enter challenges, logs all your run data and uses google maps to plan out routes.
If you want something with greater accuracy, you'll have to splash the cash on a Garmin or somesuch.
Sciatica is a b*****d, a couple of mates, and indeed my mum have had it quite badly in recent months.