internet forms - are they binding?

A few months back (may I think) I signed up to a web hosting company for my website. I recently wanted to cancel, and based on the emails I got I assumed cancelling was as easy as not paying my bill. Each month they would email my bill to me and tell me something to the effect of "your payment is now due. If we do not receive a payment within 10 days, your account will be deactivated". So I didn't pay and they charged my credit card anyway. Turns out that on their order form they have a clause that they're allowed to charge my credit card every month unless I specifically asked for them not to.

I don't remember seeing that on the order for when I read it over, but it's possible I missed it. The question is, is that legally binding? The way I see it, they could have added that clause AFTER I joined. And it's even possible I asked not to be autobilled and they simply missed my request. I know when I first signed on I didn't want automatic billing, and the dates of payments for their service are NEVER consistent (9-26 and then 11-6 are the last two), so how could that ever have been automatically billed?

Given how easily things could be changed on their end and how little real documentation there is (no, I don't save my emails, and even if I did, they're just electronic messages and could easily be modified), is it possible I could dispute this charge (I'm attempting to do so anyway) and be successful? Are there any laws that could help prove my point?

Read this article carefully and think back to when you signed on. http://www.tilj.com/content/ecomarticle09040101.htm
Did you click on a "I Accept" button?

hmmm...

The button I clicked said "Certify/Submit Order". Above it, it says "Submitting this secure form authorizes CWI Hosting, (Creative Web Ideas) for monthly recurring billing to your credit card for monthly service fees, unless otherwise noted above, or in the case service is canceled or discontinued."

Problem is, I don't remember seeing that when I originally signed on, because I specifically didn't want recurring billing and I figured I would have noticed something like that.