I need a way to make a website that will handle hundreds of transactions a day and transfer many gigabytes, perhaps close to one Terabyte of data a month: Help?

Basically, I was looking at so-called “Unlimited Hosting” plans, but they have some murky language in them. A site like Hostmonster.com offers things like Unlimited Disk Storage and Unlimited “Gigs of Site Transfer”, and they seem to be aware of and in support of Audio/Video, whether they’re for download or streaming.

Is this really the end-all be-all web hosting plan? I’ll need a pretty unfair 500gb of storage to start plus pretty much unlimited bandwidth to “move our data”.

Is this really what I’m looking for? And if not, what is? Cost wouldn’t be an issue, so to speak, but low-cost is always better :)