DVD's can go bad after awhile especially the cheapies as they grow crc errors as the media degrades over time. Are slow for doing backups. Usb keys limited for larger capacities partitions.
Easier way not relying on Windows or Linux at all is Redo Backup http://redobackup.org/
Dowload 250mb iso and burn to cd. And boot with it. Uses same under the hood engine as Clonezilla but a lot easier to use.
Easy and can back up all your partitions including Windows to another hardrive partition or external usb drive is what I do.
Then second set I just back up the Linux partitions only. So I can do clean installs of different distro's and then back them up once I have them setup and running with my programs & settings. And only takes me 20 mins to restore linux back to prior distro or full including windows in 40 mins.
And a lot easier and faster than the options presented.
And have Ubuntu 12.10,Mint 14 Cinnamon,Fuduntu,Voyager 12.10 xfce backups on a external usb drive. And last night did a clean install of Linux Mint 14 KDE. Once I have everything installed upgraded and tweaked then will redo backup the KDE 3 linux partitions also.
Then I can swap distro's in 20mins and no hassles. As have done total and just linux restores half a dozen times no issues.
Only issue is use the same partitions and don't change the size of the partitions.
And a much faster and cleaner way then DVD''s or limited size of usb keys as 64gb key is pretty expensive and cost as much as a 1tb usb external drive. A 32gb usb is the cheapest but for the cost to keep just one backup on it makes least then ideal cost/use ratio.