You have so much diskspace there, I have 2TB at the moment and one drive seems to be dieing a slow death on me. I really could do with some more and a new one to replace it. Have you had any issues with the 6870 at all? That will be one hell of a set up when you have the two cards in and the SSD hard drive, I haven't considered one of those before but I know hosting companies use them so they much be very fast drives.
Well, I have that much space because I enjoy movies and music. Music don't use that much space usually, but I have all my music in loseless quality. Which takes quite a lot of space :-p I haven't had any trouble with my 6870 card, quite happy with it. Doing remarkable well compared to price, check out how it's doing on this benchmark for example; http://www.videocardbenchmark.net/high_end_gpus.html