My 03 battery had been close to the edge since I bought the car in 06. But since it is parked indoors it was not a big issue and it kept going fine until mid-december. Replaced it with an item exactly the same from the dealer. It was a carbon copy of the original and cost me $190. Could have got it cheaper I guess but I had no time to deal with it during the day and the wife picked it up.

To avoid having to reset the electronics I hooked up the jumpstart posts in the engine compartment with JS cables to my P/U truck.

In the back I tied back the airpump to the center childseat anchor with a bungee cord and did the same with the posive battery lead (remember it is live as the other car now powers the X!!!) You could use any 12V battery and leads as the amps required with the key out of the car are not that high.

Took out the old battery and popped the new battery in, unhooked the leads to my truck, et voila! 15 minute job, tops.