I think a really quick way is to become familiar with the CollectSceneInventory.py in your RuntimePythonPoserScriptsUtility folder.  It will save a copy of a scene along with every external files used by the scene i.e. Geometries, and textures. And resave all you favoite scene.

I have actually have 2 80GB HDDs I keep my stuff on, and everynight, before I shut down I make a copy, of whatever it was working on, to that other HDD.

The new PC I'm building will have a RAID-1 Mirror, and will take care of all the copying automatically.  The only drawback there is that there have been several times I accidentally deleted or moved a driectory, and it was my fault.  And had the two drives been in RAID-1, I would'nt have had the second drive to check for the missing data...

My extra 80GB is internal, for speed, but if you do go external I suggest looking into an ethernet drive/enclosure.  Then this drive can set on your network and be accessed by any of the computer that are on.  This is great for transfering data without needing to power a pc just for the instance.