Hello I owe state taxes in California from 05 & 06 I'm currently making payments.
I know they will keep my 08 state taxes. But can they keep my federal taxes also?

Possibly, but NOT likely. It depends on how much you owe. The states CAN submit paperwork to the IRS to seize federal tax refunds, but it takes a fair amount of time and effort to implement the procedures, and they can be frustrated by the taxpayer by simply changing his exemption level to PAY taxes with his return instead of receiving a refund.

For this reason, most states do not bother unless you show that you have no intention of paying them back the taxes due.