How do I know whether I should go with the host that offers 2G bandwidth or the one that offers 10gigs?

My site is still under construction, and not yet hosted. When done, it will be a site for a small business. There will be jpeg pictures of the products for sale. A typical customer will only buy one product at a time (no need for a shopping cart). There will be other pages with text and pictures describing how the product is made.

I'm looking for experience like "my site has x amount of pages and y amount of hits and uses z amount of bandwidth." Or some back of the envelope formula like "multiply the number of pages by the number of estimated hits by x".

Also, does bandwidth get used only when visitors visit the pages, or does it also get used during admin tasks?

Thanks!

It depends on how many visitors do you get, how many pages they view, and what is the size of the average page.

Bandiwdth Needed = Number of Visitors * (Average Page size(Including EVERYTHING on it that loads) * Average page that user views views)

Well, bandwidth is really any transfer to/from the server, tasks are more cpu usage. :) You're answering your own questions today it seem. ;)

There's no exact way to calculate because you could get popular fast or ending up going through a slowdown. Basically page average + file average x average visitors. You could also try average filesize for pages & images multiplied by the average hits.