JohnthePilot

Hi Adam,
Sorry you haven't had a reply before, but I was waiting for Joe to answer the first part, but he hasn't been on today. I can answer the first part for you. You can switch the drives over as soon as XXClone says the full backup is complete. Provided everything goes OK, when you boot from the new drive, XXClone will tell you that this is the first time and ask you to check the drive letter designation. With only one drive this is not a problem. The same goes for the floopy that it asks you to put in. This is really to save you having to change your BIOS when you want to switch drives. Again with only one drive, it's not relevant so you can skip that bit. As far as the problems you are having recognising the drive, that is something that Joe would be better able to address.
With regards to XXClone v DriveImage, DriveImage is great for backing up to your external drive and once we've got you sorted out you can do that. For what you want to do now though, XXClone is the best option as you want to make the external drive bootable and switch it with your existing drive. The DriveImage itself isn't bootable, but will restore the image back to your main drive where it will be bootable. I hope you followed that OK.
As far as your last comment is concerned, XXClone should show the source and target with different drive letters. This makes me suspect there is something wrong with your USB setup and again is something Joe would be better addressing.
Regards,
John.