Thanks to all the great replies in this thread I was able to resolve Error C00D07C9 when trying to sync my Zune HD with my laptop.
Removing the white space did the trick! I also had problems finding the
"show advanced settings" option.
After changing my device name I went back to Settings/Device/Wireless Sync.
I clicked on "Use a different Network" even thought the correct network was already setup.
Selected "No, choose a different network"
Next window that came up had a drop down of available networks and underneath was the
"show advanced settings" option.
Clicked the option and verified correct network type was selected then clicked "Next"
Entered my network pass phrase and entered.
About 15 seconds later confirmation of sync setup came up.
AWESOME!
Thanks again to everyone who posted to this thread!