That's fine. You just have to watch out to make sure you don't run awry of the Dreamhost rules against taking advantage of the introductory promo codes more than once.
First, I'm not 100% positive, but you might not be able to use a promo code if you're using the same credit card and email you used on your previous account. I think you're supposed to somehow reopen your previous account. I think your original login may work and you just have to sign up for a new plan.
Second, make if you do decide that it's easier to sign up for a new account and you happen to use a promo code (which I think is a bit iffy but who am I to say), remember that you won't be able to add any domains that were previously hosted here. So if that domain you have hosted over at yahoo is the same one you had with your old Dreamhost account, this will create trouble in that particular situation.
Basically, you'd have to pay the same that you'd pay signing up as a new customer. You have your choice of paying monthly (and paying the $50 setup fee) or pre-paying annually or with a multi-year prepayment. BTW, the days of the $22.40 first year account are over since Dreamhost capped promo codes at $50 off.
Beyond the questions I've already addressed, are you asking about how to transfer your site? If so, you should take a look at the Dreamhost wiki article on transferring hosting to Dreamhost from another web host.
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