In QuickBooks for Mac, open the company file that you would like to convert to a Windows file.
Choose File > Back Up to QuickBooks for Windows.
Choose the name of the file you want to convert and click Save.
On the Enter Password window, enter a password for the file. Or, if you do not want to password protect the file, just leave the fields blank.
Click OK. QuickBooks will then create a .qbb file. You can then click “Show File in Finder” to locate the file on your Mac. QuickBooks also creates an instruction PDF file in the same location and with the same name as your .qbb file.
Send both the .qbb file and the Instruction PDF file to the Windows user using MobileMe, CD, or USB drive or some other media. (Most Macs read and write data to and from PC-formatted media.)
On the PC
In QuickBooks for Windows*, choose File > Open or Restore Company and follow the onscreen prompts.
When asked to update the file, mark the checkbox and click Update Now.