Your daughter must be a full time student to claim Earned Income Credit for her. She must be UNDER age 17 on 12/31/04 to claim Child Tax Credit for her and she must be your dependent.
Your child tax credit for your son(I assume he is your dependent)will be 1000 max. This amount is limited to any tax on the return. If your tax is reduced to -0-, you MAY be eligible for Additional Child Tax Credit if your income is more than 10750. Use form 8812 to compute the amount.