i use outlook 2007 at work on my work login, but use the webmail interface when working out in the field. if i need old emails, ill load up my domain account and get them. for personal, i use the webmail for my isp as well as gmail. overall, i manage 5 email accounts for different reasons. 2 are outlook the others are webmail. i havent had cause to change from outlook, its been pretty decent for our needs here at work.
edit:
i didnt vote, because even tho i dont use a client on my personal puter, i dont find it useless at all.