Instructions:Don't know how good this offer is it is but it's better than nothing in my opinion getting an Amazon voucher if you do decide to continue with the dvd rentals after the free 30 day trial has expired.
Saw this on the Guardian website today.
In order to qualify for your £20 Amazon shop voucher, you must validly register for the free trial and make your first DVD Rental monthly payment.
The cheapest package is £7.82 so a saving of £12.18 to be had (£20 Amazon voucher minus £7.82 cost of one month rental payment)
This offer expires at midnight on 31st December 2008
Full details when you click 'use offer' link