How should I choose between GET and POST methods in HTML forms?

Question

I wish to know all the pros and cons about using these two methods. In particular the implications on web security.

Thanks.

Answer 1

David M's answer get's my vote.

I just wanted to add one item that I heard about, maybe it was an urban legend??

Someone had a site with links that were only for internal use to delete files on their website. All was well until a webspider ( I think it was google ) somehow found these links and merrily followed each one causing all the files on his site to be deleted. The links used GET and should have used POST as spiders don't follow POST links.