> Although, if you never use a card it probably wouldn't affect your rating at all - after all it doesn't say anything about how well you handle credit.

My understanding is that having a card and never using it IS actually good for your credit rating. I've been told it's a good idea, when you're a teenager, to have a credit card that you're not allowed to use, as then you get credit when you may need it later. But I don't have any evidence to support this theory, and I don't even really know where this impression originated. And, for all I know, if it were once true, it may not be anymore.