How do you track down a person when their name has changed?

Question:

How do you track down a person when their name has changed?

Recently my Uncle has passed and he had 2 Kids - The mother had left my uncle with the kids (when the kids were small) and no one had seen hide nor hair from any of them since. My question is this... How can I find out where the kids are to let them know that their father has passed on?
The mother most likely had remarried and changed their last name. -
Is their a way to do this on the internet that will not cost any money?
I've tried the free people searches - but they are garbage - do you know of a site where they may list family history or some way to track name changes?
Thanks to all who answer

Best Answer - Chosen by Asker: I wouldn't make the assumption that the mother's remarriage means the kids lost their father's name. If you have their names and dates of birth, you can find them in about 2 mins on ancestry.com or one of the public record search sites. Don't laugh, either. I was in charge of my high school class reunion search committee. No one stayed in central Michigan in the early 80s because of the horrid economy. 150 people hadn't been heard from in 25 years. We found 147 of them through Ancestry.com and intellius.com in less than a week. It didn't cost us anything other than phone calls.

My dearest suggestion is to find his original marriage license to her and figure out who her parents were. Then track down those parents, alive or dead. If they're dead, find the funeral home who handled the burial and ask them to forward a letter from you to the grandchildren because of the passing of their father. I'll guarantee they'll do it. If they don't have current info, they'll have a copy of the obituary and can at least give you more recent info than you probably have. You can do the same to find any brothers/sisters she had, as it's likely someone kept in touch with her and wouldn't be so cruel that they'd keep the kids from knowing their father died and where he is.