All you need is Microsoft's "Your Phone" app and Samsung's "Link to Windows." You can long press the files or photos you want to move from your phone, then select all the ones you want to transfer to your PC. To transfer files from PC to phone, just drag and drop them to the "Your Phone" window.

There are a few caveats. File size is limited to 512MB, so it won't work to get larger HD movies from your computer to your phone, for instance. Transfers are also limited to 100 files, so sending a large batch of photos from your phone to PC also won't be completely seamless. Finally, your phone and PC will need to be on the same WiFi network and the service requires Samsung's Link to Windows 1.5, which isn't necessarily supported on all Galaxy devices.