If my children were adopted out can I still carry them on my taxes

Did you provide more than 50% of there support for the year 2008/ if not then no

If they were adopted you no longer have any claim to them so no,
The adopting parents would be filing claiming them so it would be fraud if you did too.

You would have to prove support

They must live with you for more than 6 months and you provided more than half of their support. They should not be Qualifying Child of any one else.
Read about Qualifying Child: Your U.S. Tax Return: Requirements for claiming a dependent

Sorry, but if your children were adopted by someone else, then legally they are not your children anymore! Hence, you cannot claim them on your tax return.

Children who are adopted, are now the legal children of the other person. Only they can claim them.