server bandwidth question

I am in the planning stages of starting my own site, which I obviously think will be a big hit. Can someone explain to me why it would be better to get a dedicated server, over a comparable shared server or whatever. i want 0 downtime, and no slowdowns. Can anyone recommend a place to check out? I have no intention of hosting videos or anything big, just basically the actual frontend, which will be collecting information to put in the database in the backend, and I guess querying the backend database very frequently.

What are the specs on the hosting for a site like this, and what do you think it is on a site like ebay, amazon, etc.

I am just trying to understand what it is I need without getting ripped by a salesman.

[quotef7b990228e="freedesktoppc"]which I obviously think will be a big hit[/quotef7b990228e]
thats what everyone thinks, jk

[quotef7b990228e]Can someone explain to me why it would be better to get a dedicated server[/quotef7b990228e]
You should never inest into a dedicated until you are sure you need it. Most times, even realtively big sites run on shared. However, for a large assortment of small to big packages. Try http//admhosting.net , they always have specials and you can custom order if you contact the owner. They own http//itsactuallyfree.com and they have a HUGE following from the Newgrounds.com users.

Not looking for a great deal, per se, looking for a known company that I don't have to worry about.