I have to file my taxes for 2008.
I entered data in Turbo Tax
Based on Married Filing Separately, it shows huge amount as return
When I put Married filing jointly, it shows very less amount.

I'm married and I'm on H1. Since my wife is on H4, she can not earn any income in united states. My wife and son are here with me since 2007.

Is it required to file tax returns for her?

Will it be legal to file Married filing Separately and make my wife and 3 years old son as dependents.

Please advice.

Thanks in advance.

Evidently, you make doing something wrong. Your refund on separate return can not be more than that on the joint return.