In reply to steveb2006:
not sure about free ones, but some flavour of sony vegas (depending on version of product you can buy this for £30 upto £200) or Adobe Premier elements (about £50 or £65 bundled with Photoshop elements) are the normally recommended options. it depends what you are trying to produce, more than one camera, how often you might actually use it.
if it's a one off, then you might almost be worth following some youtube tutorials first and then going for a free trial of one of the adobe products when you understand the basics of that program?