For year 2007, The State Disability Insurance (SDI) withholding rate was 0.6%. The taxable wage limit is $83,389 for each employee per calendar year. The maximum to withhold for each employee is $500.33.
See http://www.edd.ca.gov/taxrep/taxrte9x.htm#sdirate for more rate information.
So, if none of your employees made more than 83,389 the SDI total wages are 129556.92
Or is any employee had more than 83,389 only count that maximum for that employee when you figure SDI wages.
I hope this is the information that you need for the SDI wages for 2007.