I have to say that of all the current non-business mail clients I prefer Windows Live Mail. I agree it comes as an initial shock, but once you get used to it, it grows on you.
Thunderbird I dislike for several reasons
First the way it tries to force the "smart folders" view by default
More importantly if you are using several mailboxes, trying to set out multiple outgoing SMTP accounts is simply a non-intuitive nightmare. If you've only got one account, then the problem doesn't arise
I don't like the layout either...
Personally I think the new open source version of Eudora may be better. Its Thunderbird with a front end designed to look like the old Eudora program - its worth considering