www.virgin.net Virgin.net offer pop3 mail as well as web access. When you view the mail using web access, the mail will remain on the server thus allowing you to download it later to Outlook when convenient.
AFAIK, with some web based services, once you view your mail, you can't subsequently download it - (although it will still be available on the web server).
I think Virgin also offer a free facility which will allow you to forward a copy of incoming mail to an alternative address - eg your Yahoo account.
They seem to have various packages including a dial up pay as you go service.