There's a bigger reliability issue with raid 0 than with any terabyte drive
[pedantic]Raid 0 isn't strictly speaking a raid, since there are no redundant disks. [/pedantic]
12gb of ram will not help overclocking, consider carefully whether you'll actually be able to push the system past 6gb before getting the second set. Ideally buy one set, and if you ever manage to run out then buy the second.
"Gaming and encoding" remains terribly unspecific. What games, what res, what encoding? Which matters more? P55 or AMD is likely to dominate for gaming at this budget, but for encoding the X58 chipset will be quicker.
I have a suspicion people quote encoding just to encourage forum people to quote the processor they've decided they want, rather than one which actually fits the requirements. Do you
really care if it takes one hour or two to rip a DVD, when you can queue several and leave it running overnight?