Dave, Here is a slightly different methods to accomplish the same thing. I wrote it for XP but read the process and modify it slightly for Win7. It should work. Here is the procedure to follow that should allow you to transfer music, photos or documents.
1. Setup and turn on all your equipment to run on your wifi network . On the PlayBook you want to get its IP Address and write it down on a piece of paper. This number can vary each time so it is best to get the info just before you start. On the PlayBook go to the settings Gear icon (top right of screen) and tap Storage and Sharing. Toggle on the WiFi Sharing. Remember to toggle it off when you are finished or you can set a password to keep hackers out. Then go to the top of the left pane to "About". In the right pane tap the dropdown arrow and select " Network". Go to the line IPv4 and write the IP address on a piece of paper. It should look something like this 192.168.0.100.
2. On your computer, click on Start, Click on My Computer. In the address line at the top of the page, clear it and enter two back slashes such as \\ followed by the IP Address of the PlayBook. So the line should look like \\192.168.0.100 and then press enter. In a short time it should read the directory of the PlayBook. Click Media and it will show all your subdirectories. At this point you can open the music directories of your computer and drag all the music you want over to the PlayBook. Place it in the Music directory. Pictures will go into the camera directory, movies to the video directory. Documents to your document directory.
3. If you transfer any music, at this point you can go to the PlayBook and try playing some music to see if it works. I have converted all my music to MP3 format on my laptop and then transferred it by wifi to my PlayBook. It will only allow you to transfer 5000 selections if I remember correctly.
4. You can exit your laptop and on your Playbook go to settings/ storage and Sharing and toggle off WiFi sharing or put a password on it.