I've gotten Gmail to work in Thunderbird, but I prefer webmail.
My mom had troubles with Outlook Express so I managed to switch her to Thunderbird. Otherwise, I wouldn't have had a chance. Also when she reinstalled XP (again), I made her a backup of her email by copying the profile folder. In Outlook, she had to copy every individual one, although I don't know if you can copy the profile.
So she was asleep when I reinstalled Thunderbird for her, and then she woke up and checked her email and yelled at me to come, because she had no idea how all her emails didn't get lost.