Refferal/Affilliate System Plugins

Hi Folks

I am putting a site together for my offline business and need to find a refferal system plugin.
I want my customers (we install Alarm & CCTV systems in houses) to be able to
1) Sign up at my site…
2) Automatically recieve a unique link which they can then use to refer friends via email, facebook etc…
3) Have the referrals tracked by me, so that i can somehow reward them, after their friend has had their system installed and paid for it…

Is there a good, easy to use plugin out there, which will do the job?

Thanks

Steve