Image paths and virtual account then to main account

I am using 2.5 and would like to know how I can get this to work.

When I setup a new account on my machine, the account is at:

http://new.accounts.com/~accountname/ac ... esite.com/

I want to be able to upload images and see them in the editor window as well as in the finished layout of the page.

When the site is live, the account will then need to be: http://www.accountnamesite.com and the images should work again.

Any suggestions on how to get this to work?

I have looked around at a number of other solutions, but none seem to deal with this exactly.

Thanks.