To be clear, the specific path the script is reporting...
\\192.168.2.20\H$\[artist]\[album]
...is valid? In other words, you can go Start -> Run, paste in the path the script reports, and when you hit enter it takes you to the correct folder? If you change the alert code from this...
alert("artFolderPath: " + artFolderPath);
...to this...
prompt("artFolderPath: ", artFolderPath);
...then you will be able to copy and paste the path that it alerts. If you really can paste it into Start -> Run and it opens the remote folder, then the script should be able to access the folder in the same way.
Again, to be sure, you followed the instructions in the first post of this thread that say to set a registry value that makes "My Computer" show up in Internet Explorer's tools? You have to enable "Initialize and script ActiveX controls not marked as safe" under the "My Computer" zone, not in any of the other zones.