question on possible income tax return

[jaeSun]

i used a calculator to estimate my tax return for 2004. what i got, was, unbelievable.

background: i am a student, married, with 1 kid. i made very little money ($18,500).

i did the calculation, and the only deductions i claimed was my college expenses (lifetime learning credit) for $2000. i am filing married jointly. i am 23 years old, and wife is 19. wife did not work.

i paid $1500 in federal taxes last year. (i claimed 0 on my W2, so they took out as much taxes as possible).

and the result?

(sorry about the big picture)
http://hosted.whiteazn.com/tax.bmp

the explanations they gave for the extra $3000:

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">refundable tax credits:

These are tax credits that are considered the same as payments since you can receive these credits even if your tax liability is zero. Usually credits only reduce your tax liability to zero. These go beyond that.

Earned Income Credit:

The earned income credit is a credit available to working Americans. It is calculated based on your income and the number of so-called "qualifying children" you support. A qualifying child is a child, grandchild, or foster child who is either under age 19, under age 24 and a student, or disabled at the end of 2004. We estimate your earned income credit based on the information you enter about your dependents and your income.

The maximum earned income credit for 2004 is $4,300 and is available to taxpayers who earn $10,750 - $14,040 and have two or more qualifying children.

The earned income credit is treated on your tax return as a tax payment. This means that if your earned income credit is larger than the amount of tax you owe, you receive the excess as a tax refund.

additional child tax credit:

If your child tax credit is larger than the amount of tax you owe, you could receive the additional amount as a tax refund. The amount you are eligible as a refund is equal to the excess of your earned income (wages and self-employment income) over $10,750.<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

ive heard people getting more money than they paid into because of the child tax credit, but i just want to make sure. its very suprising to me to get this much money back (i have another kid on the way!)

thank you in advance

[jaeSun]

also, i should ask, what is the difference between personal exemptions and the standard deduction. trying to read up more about my tax return (above), and its deducting my standard deduction ($9700) and personal exemptions ($3100 per dependents, which is 3 for my family of me, wife, and kid)

sorry for newbie questions. only 23, did my taxes myself with software and just always plugged in numbers, (which typically got me a refund of all my tax)