ask help from STP

WE filed 1040NR-EZ from 1998 to 2002 since we are F1 and my wife no income.
in May 2003,I changed F1 to H1, in Sep 2003, my wife change F1 to H4. My annual salary is 49000.
so my question is:
1.we should file 1040 jointly right?
2.my taxable money in 2003 should be:
49,000-4750*2(standard deduction)-3050*2(exemption)-1000(my wife's tuition in school)=32,400.
3. tax hold in company is 5000, and find table should pay tax is 4,164. so they should give me 836$ back.
Am I right?
thanks for you sincere help.