To import mail from yahoo, use YahooPOPs... for hotmail, you can directly configure Outlook Express. For details, search in google.
SMTP and POP are protocols for sending and receiving mail respectively. Kinda like HTTP is protocol for documents sharing in internet.
Once you import mails to Outlook Express, you can view them offline...
Arun
EDIT: Corrected as pointed out by godsownman... Sorry for the error...