they have the benefit that they have registered lots of surnames so you can often get your [email protected] email address.
It is a cost, but not much (think about 20 quid a year) and I don't get any spam at all. Some of that will be due to the fact that I don't use my email address much on public sites/friends joke lists etc. Some of it is because they are less of a target than guessing all the names at yahoo. Thought of setting up a new one at yahoo/hotmail and seeing how it goes?