The way to go with this is an external HD. DVD image backup is not reliable.
Until you get an external, send it over the network to the C: drive of any other network computer, or put it in a primary partition on your HD or, better yet, another HD you add for that purpose.
Cannot agree more with multiple HDDs; placing backups on the same disk that you are backing up invites pain (you are protected against OS crashes but not disk crashes). Secondary storage (additional HDD/mem sticks) today is dirt cheap and, given the importance of backups, essential. If image backup size is an issue, consider a partition on which you place ONLY the OS and apps. Two reasons: it is, almost exclusively, the OS that is going to become corrupt or attacked and, therefore, require periodic attention. Secondly, by limiting the amount of data on the OS partition, image backups will not be so large as to require extraordinary storage space.
I also agree that optical storage is not a good idea due to degradation or read-write errors. I store supercritical data on mem sticks, in addition to storing it on secondary HDDs. Dedicated mem sticks for docs, MP3s, JEPGs (if those are supercritical data) fit nicely on 16GB sticks that cost $30 bucks a stick.
Monk