The problem with most recommendations for spam blocking utilities is that you don't know whether the blocker is working for you, or whether the spammers just haven't discovered your address.

Has anyone who was getting a lot of spam blocked it with one of these utilities without also changing their address?

Even hotmail has a fair "filter," and they manage to send about half of the spam to junk mail. The problem is that the spammers fake return addresses, send with multiple different subject lines, and numerous other tricks, just to confuse the filters. It's not uncommon to find what is obviously the same message at least twice in the inbox and five or six times in the junk mail - each with a different "id" and all sent within a few seconds of each other.

It's been mentioned before that you should be particularly cautious about allowing your kids to use "cute" nicknames as an email address. "Cuddlebunny" and "sweetstuff" will invite a particularly obnoxious kind of spam. Just about anybody (sufficiently perverted) can pick out the "currently popular" nicknames kids use, and send at random until they get an answer.

A "strong" address, containing a symbol or two and maybe a couple of numbers can significantly reduce the likelihood that your address will be found by a "random sequence generator." A relatively "long" name may give a little help. If you use numbers, they should not be consecutive: john42 is not nearly as good as j4hn2.

Most sites treat email addys as not "case sensitive," so just mixing upper and lower case won't help much; but if I were to use j0hn_1n_kans2s (3 numerals and one symbol) they at least have to include 26 letters + 10 digits + a half dozen symbols in their "randoms." This raises the number of possible sequences rather significantly, and may prevent, or at least inhibit, them from finding you.

There is some indication that spammers avoid addys that "look like a business," although that's kind of an "iffy" one to rely on.

John