Hi Andy,
I don't think there is a right or wrong answer to this question, just a personal preference. I don't use an email signature. I can understand when you would want to limit sending and receiving them if you are sending and receiving from users that are still on slow dialup connections. Legal disclaimers are a waste of bits. If you have a short email signature with no graphics that's always fine by me. Another thought to keep in mind if you do want to use large email signatures is to be considerate and remove them from emails before sending them to listserv's and newsgroups.
Hope that helps!
-Raymond