Hi Jenn
I completely concur with Linda's advice and Larwee's references regarding hosting. If you are anticipating hosting a forum, and see it taking off, cheap hosting will end up being a nightmare in all probability. Web Hosting Talk is always a good place to do some research and get opinions from other users past and present so I'll add my recommendation.
I don't use SBI but reports about them are generally favourable. Certainly for non technical people they often provide a great and easy to manage solution to getting a website up and running quickly, and also claim to take care of promoting your sites in the least time consuming way possible. It's really a question of a) whether they can provide what you need and b) how much "control" you want when it comes to your "webmastering". As far as reliability goes, I think they are pretty solid, at least as far as reports I've seen.
Yes, unlimited bandwidth is a marketing misnomer as someone has already said, but, I wouldn't say that it is a reason to dismiss a hosting company out of hand - "overselling" is common practice nowadays in what is a hugely competitive field. Again, Larwee and Linda's suggestions are very good advice when embarking on the difficult task of choosing the right host
for you
What no-one has mentioned yet is that if you want to establish a forum, most good hosting companies will provide the better known scripts which you can install pretty easily on your domain, particularly if you look for a host offering Cpanel and Fantastico which can take a lot of headaches out of the donkey work. As a starting point, shared hosting with a reputable company should suffice and the forums will give you a feel for how well they perform in terms of tech and customer support (vital consideration). Again echoing Linda's coments, you will always find the odd moaner on any hosting service so bear that in mind, try to concentrate on the ones where the latest information provides overall good feedback and obviously avoid the ones that seem to throw up nothing but complaints.
Without knowing what your site is going to look like or deal with it's difficult to give any more than general advice but you may want to consider whether a traditional static site is best, or if you would be better off using a CMS (content management system) such as Drupal or Joomla . These can be intimidating for first time users though and are not everyone's cup of tea, but they deserve a mention as a valid alternative to building a staticsite with traditional HTML editing software. Failing that, you could also consider Wordpress which can be used for more than just blogging. Again, all of these should be available through a good host offering C-Panel and Fantastico.
Dreamweaver is a great piece of software, but as you are finding out, it takes a lot of study to get the best out of it and there are easier ways nowadays to design and build your sites.
I'm sorry if this answer has just added more variables to your quandary, but the more information you have before you choose a given path, the better.
If I think of anything else, I'll add it later!
Mo