Webhosting & List Management

Hi,just two questions :

1. Does anyone know how much 150MB of disk space and 10 GB of Bandwidth a month translates to (eg. how many webpages and how many visitors etc.) ?

2. What list manager is good for a list of 19,000 subscribers ? I'm using Aweber right now, but, I can only host one list. If I want more lists, it costs much more. I heard that Get Response is the best. Is this true ? I'm looking for a good deal that I can pay a year in advance (if possible) and get a discount.

Thank you very much.