wm5torage is a nightmare to get working, especially on newer ROMs.
Its possible, but I don't recommend bothering anymore.
Best way (if not the fastest necessarily), is to use mochaFTP:
http://www.mochasoft.dk/freeware/ftpd.htm
When you run this program, it turns your phone into an FTP server and tells you your current IP address.
Type this address into Windows Explorer, and BAM! It shows you the contents of your entire phone's storage directory (complete with storage card, extended rom, etc), and you can drag and drop files like a network drive.
Only catch is that you're limited to the speed of your internet connection. So, better to do this with WiFi or at the very least a strong EVDO signal.
This is also useful, by the way, to have friends remotely copy stuff to your device. You could tell them your IP address and have them upload something to your phone half way accross the world since its over IP!