Ah, yeah, you're right.... hadn't realised. It's probably easier therefore to use the following link, and then select the 12 month option...
https://panel.dreamhost.com/signup/
Thanks for pointing out that.
Like Tricky, I'm not sure what the catch is (there
has to be one somewhere)... maybe it's that they're registering the new domain names in their name, and they'll charge a fortune when/if you want to switch providers...?!? I dunno. But, for a fiver for a year, I'm not gonna complain.