Veronica Belmont pit Yahoo Mail (beta) against most geeks' favored e-mail service, Gmail. If you're aiming to dump your current PC (or Mac)-based e-mail app and move to the Web, this is a good, basic comparison of the strengths and weaknesses of the two services.
I'll tell you right now that Gmail won, by a nose. Click through to the video to seehow Gmail performed in each round of the fight: Interface, Features, Speed, Organization, and Security.