Make sure you connect the 1541 to the ZoomFloppy first the turn the 1541 on and then plug the USB cable into the ZoomFloppy.
Turn it off the exact opposite of turning it on
Also get CBMXfer which is a GUI interface for OpenCBM. Makes life a lot easier.
I second the parallel cable option. I got mine off eBay for $15 and it's well worth it, especially for speed and nibbler (copy disks that are copy protected)
You are going to love the ZoomFloppy for sure!
Programming is like sex, one mistake and you have to support it for the rest of your life.