Hi Kelly
Dont discount the battery as it may be the problem just because the lights etc are working dosent mean that its ok , If it hasnt got enough amperage to turn the starter motor over fast enough it may not fire up the engine but seem ok otherwise , May be best to get it checked by a good auto electrician and replace if necessary otherwise you could end up buying lots of parts you dont need and still not solving the problem , A good auto electrician will be able to sort the problem by replacing only the necessary parts .
Graham, November 2009