Message to users when they sign up with details

The Membership plugin is great, I've stumbled across loads of techniques, but what I would like to do, is to send an automated email to the user once they sign up with their details and a little, thank you for joining (nicely designed, in HTML).

And would also like to have another email sent 2 weeks after 'asking how everything is'.

So two automated emails is what I want after sign-up, one immediately, and the second one two weeks after they signed up.

Any help with this?