VABlitz: The best option would be two portable hard drives.
That's what I'm doing with all my stuff since losing most of my music collection in december due to a failed (new) harddrive... I would have lost all my sheet music, pics etc.. too if I wouldn't have worked for days to save as much data from it as possible.
Although I don't use a case for these anymore, got two HDD hubs attached to my PC, this way I can switch between as many HDDs as I want and if something is broken, I can see what it is faster and replace it without having to send case+drive in for guarantee stuff. Being able to use 3,5'' and 2,5'' drives like SD cards is grand.
Funny thing is: I'm currently making a backup of the HDD with all my games from GoG, HumbleBundle, IndieGameStand, IndieRoyale etc...
There are no reliable harddrives made anymore, I'd pay a lot for them, but there just isn't one.
I even had an expensive NAS-drive fail after a short while and cheaper drives run like a charm for ages with heavy workload.
Currently I'm using multiple 2TB Seagate Barracudas (with NTFS), since the others failed and the old excellent ones from Samsung are just not big enough for me anymore.
I know that they are not perfect either, but I got way too much stuff to burn all this and burn it again after updates etc...
2TB because it's the maximum size still working with WinXP without problems, although my Linux could handle more.
If you don't have as much stuff as me, the 2,5'' Samsung 1TB drives are a very slick solution and extremely portable in addition to that (fit in the same hubs as the big ones).