As long as you know your email address and password follow these instructions to setup Windows Mail, they may say Outlook Express but they are identical to set up.
http://www.virginmedia.com/help/emai...ed/oe6-ntl.php
Also ensure that the is nothing in your Windows Mail Account which means emptying the inbox, sent items, outbox, deleted emails and any folders you may be using as you only have 30Mb of space in your mailbox and all the above take up that valuable space.
Also check in your NTL webmail folders and clear every file out of there as well.
http://webmail.ntlworld.com/
If you need to keep anything that you remove then save it as a word document or similar.