I used to use an external USB drive to take full and incremental backups of my C:\drive using Dantz (EMC) Retrospect. It was good but it was clunky and took too much time to run a full backup even with USB 2.0.
This new system I use takes less time and negates the need for having to reinstall Windows as a first step to Disaster Recovery. I still do a once-per-month external backup as I used to but for day to day DR purposes I takes snaps each evening.
Give it some though. Tape is dead and CDs are too small. Even DVDs are too small if you have lots of data to backup like I do.
Not a bad idea.
Currently I need to back up about 4 gigs of data (patches, software I've collected over the years, etc.), in preparation for (eventually) replacing this system. For that, I'm still leaning towards a CD-R or DVD/RW drive.