1) Are we talking about Microsoft OUTLOOK or Outlook Express right now? They work differently, so advice for one won't be directly applicable to the other.
2) Presumably you have been given an e-mail account on the new domain by your ISP (james_s@domain.com or something along those lines) and a password to go with it. (That is, the ISP is really running the post office for your domain, and you aren't administering it directly using a server and a program like MS Exchange.) If so, you'll need that information in order to set up either Outlook or Outlook Express. Just having the POP3 and SMTP servers isn't enough.
I suspect you'll get the best results by contacting the tech support department at your ISP, since they presumably know how things are done on their end, and what you need to do on yours. Since this isn't a typical "I signed up with an ISP and they gave me an e-mail" situation, it may be harder for third parties to offer useful advice.
Forwarding to MSN is something that you'd have to set up
after setting up whichever version of Outlook you plan to use (
don't try to set up both programs for the same mailbox on the same PC, you'll confuse the hell out of yourself.

) BTW, why forward the mail to MSN? You're going to have to access both accounts anyway unless your ISP offers some kind of server-level mail forwarding.
Regards,
Joe