I need to file a 1040x on my 2005 returns, do I need to file my 1040 first?

My wife and I were going to file as Married Filing Seperately on our 2005 Tax Returns. She has alfeady filed and received her refund long ago. I have yet to file. I was able to find out later that our refund would be much greater if we filed jointly. I understand this can be corrected with a 1040x. Do I need to file my 2005 1040 first and then submit a 1040x later, or can I file them both at the same time?