yes, either mozilla or definitely thunderbird can import old netscape 4 (which is what i am guessing you are using?) profiles. after that's done, you can use the account settings options to change the mail server, your email address etc i.e., in mozilla/thunderbird, unlike netscape4, these fields (your email address, the mailserver, etc) are configurable.
of course if you were using IMAP (or even POP) to store your email in remote folders on the covad mailserver, that stuff is going to be lost.
i need a bit more info, so please ping me offline if interested. i replied online so i could pitch mozilla ;-).
--ravi