Since the drive was previously formatted (it's no longer RAW), you can just open up My Computer, right-click the external drive, and select Format...no additional software required. On the other hand you could simply delete the files on the drive you don't want and continue using the drive...you shouldn't have to reformat.
Hope this helps,
I've got an 80 gig external hard drive, that I wanted to use strictly for backups. I used a backup program the other day, and now realize I don't like it. What would be the best program/app to erase that external drive?