Western Digital Caviar Black Question

Hello, I've been wondering if it is better to get two "WD1002FAEX 1TB" drives instead of one "WD2001FASS 2TB" drive?

I need to have a partition for my PC games installs and another one for data storage from my old drives (I'm retiring my old drives because one is about 7 years old "WD 80GB IDE" and the other one is about 6 years old "Maxtor 250GB IDE")

I know that the WD 2TB is a tiny bit faster than the WD 1TB but I have a feeling that having two separted drives whould be more reliable, safer for long term storage and maybe faster than a single massive drive.

So, what do you guys think about my decision?