Me too. And one post is from 10/02.

It is a public board.
Provided DB is not giving away Personally Identifiable Information, it matters not if you change your username as whatever name you use is potentially catalogued I think by search engines.
When DB axed the entrance top 10 list, I think that stopped most of the post indexing.
Are not all IPs associated with usernames in posts?

If a person is really concerned, using an anonymous proxy would help.
Dial up helps.
Broadband is sticky as the IP doesn't change.

Really, just think before you post.