I have not been able to use the "Transfer and sync" function either. I tried playing with it and when I click to "Select a device" it searches indefinitely and no devices show up on the N900. But with bluetooth the N900 does pick up the PC and I'm able to sync with PC Suite.

At least you can send files to the PC through PC suite. If your N900 is paired with your PC, you can also just open the N900 through "My Computer" (if you're on a Windows system) and drag and drop files whever you like.