Hi All...New Droid owner and I was having fit trying to get stuff on the SD card, I was playing around and this worked for me.
When I plugged in the USB cable, I pulled down the notification bar and the USB connection says Select to copy files, etc. So, I selected it. It asks you if you want to mount or unmount. I selected mount and the SD card came up in WinXP, just like any other drive. Now the notification bar for the USB says Turn Off USB Storage turn it off and it goes back to normal.
Hope that helps some of you!