|Trailing in after OtH and Fingers... who have covered much of the ground variously re' possible options... (and thanks to OtH for the update re' Maxblast replacement by Seagate)...|
Re' saving as in imaging or similar a partition and its contents... I seem to recall that Acronis allows you to disk-span an image for a drive that is too larger for one optical disk. Not sure about the WD freebie version as that's likely a very cut down version with limited options). But the full paid for versions do (if I recall correctly) allow that path - multiple disks. Thus if you have a large drive and or partitions various... you can image them that way. Does Eseaus allow similar?
Similarly I think Acronis etc. (Eseaus too...?) "may" allow a simple copy routine - across more than one disk. This copy can (usually) be read/accessed by most current OS - as it's in form of readable files etc. Whereas a true backup doesn't allow that option - readable/accessible by another OS - other than to actually restore it to a drive/partition.
Windows backup is not an actual copy either. It's in the form of code that cannot be read as usable data by any system (other than to be restored to a given location). But when restored returns all data etc. to the destination drive/partition.
The obvious benefit of disk-spanning is that you don't need another large external drive; although they are cheap enuff these days...? Disadvantage is that you have to keep them secure and avoid losing or breaking them. I favour both methods for critical/important stuff...
Regardless of current situation, always wise to make copies (rather than true backups) of all data etc. off the system entirely; and to check them occasionally too to ensure they are OK. And if anything really critical (stuff you simply wouldn't wish to lose) then make two sets and keep in safe places apart from each other. And even better make a copy to an external hard-drive too; be it usb or a NAS device (Network Area Storage) which can be accessed over a wifi or cat-5 etc. lan. Actual copies rather than true backups allow you to option of accessing the contents at any time on any viable/working system...
Obviously update the copies too at intervals - by making a fresh set (new disks); and keep previous set until you make a second or third or whatever update/copy... That way you have latest and the most recent prior to newest at all times.
Going back to your query for a path to preserving E; partition (you data/files area?). Time was when recovery routines allowed a partial restore to delivery state and/or a full restore to delivery state. The former didn't (one believed/hoped) touch other than the primary that had the OS etc. installed; the latter did wipe the drive fully and rebuild as delivered... with obvious loss of all data... Sadly that went a while ago and a full destructive restore seems to be the norm nowadays? And this happened prior to arrival of Win-7 (depending on manufacturer of your system).
The gurus nonetheless always advised to safeguard data somewhat along the lines above; and certainly before running any allegedly safe partial restore disk routines (just in-case...). Similarly if/when restoring/re-installing/rebuilding an OS, be it via a repair routine or restoring an image from another saved elsewhere.