Nah probably just an old drive lol, the thing has been through two (or 3?) PCs that I built.
I still need to save up money and buy some new HDDs (maybe Hybrids?, probably just stick with mechanical) a new GPU (I like my 560Ti but I probably have enough PSU power to go up a few steps) RAM is good... motherboard should be fine, I still need a different non stock CPU cooler.... hummm ... maybe more case fans....
and lights, red was it that made it faster?
Depends on your needs on the hdds.
I'd be using them for media storage (games, videos, pictures, etc etc)
Not sure if i'll opt for 2+ or just get one massive one.
I have a dedicated external for my photography stuff, but I could possible put them on an internal as well just so I have some redundancy.