you just need to copy the ~/Library/Mail/ folder over.
the plists in the prefs folder only deal with window positions etc...
Hmm...I don't think so. Try moving com.apple.mail.plist out of ~/Library/Preferences and relaunching Mail. You'll find all your accounts gone (except your MobileMe account, if you have one).
Or, in Terminal, take a look at the output from
defaults read com.apple.mail MailAccounts(Gee, this
rings a bell!)