[Bish0pQ]

Nginx is more light weight. I think that should be enough, but if you're starting an upload service you're going to need more than 130GB storage, though that will be enough for the first weeks/maybe even months depending on how much people will use your service.

What software will you be using? Will you be using the pomf software as upload site, since I think that is pretty lightweight.
I think a GB should do the trick, but you should check out what your server does under stress testing. This is where you can actually use DDos attacks for. Not for taking someone's site offline like a skid, but checking if your website can handle big loads of traffic.

Beware that you don't use too much of your bandwith though. Also are you using custom scripts you wrote yourself or existing ones?