2009 for MAC backup restores on 2009 for PC
2009 for MAC backup still in 2005 format. How do I get 2009 format backups to use on a 2009 for PC machine??
2009 for MAC backup still in 2005 format. How do I get 2009 format backups to use on a 2009 for PC machine??

Assuming that you upgraded your QBP 2005 for Mac file in QB 2009 for Mac, in QB 2009 for Mac use File > Back Up to QuickBooks for Windows to create a file that QB 2009 for Windows can open.
If that's what you've already been doing, please explain what makes you think the file is still in QBP 2005 for Mac format.
The file properties of the 2009 for MAC Windows backup shows as 2005 QBB format and when restored on 2009 for PC, shows as 2005 format QBW.
The 2009 PC then recognizes that and notifies that a conversion process has been initiated. That process fails.

gspbuy, is your version of QuickBooks 2009 for Mac fully updated? Use Command-1 to check. the current release is R6.