The Thermaltake Armor would be just fine. It's one of the most popular full tower cases, and it's a great case. I just put out that Antec 900 because of it's price. It can fit an 8800GTX....but again it's your choice. The Armor will do well.
The Tuniq is
one of the best HSFs out there. It's recommended a lot, because it really cools. Another cheaper alternative, that I forgot to mention, is the
Arctic Cooling Freezer 7 Pro. This would do fine, for the e6750, and much cheaper than the Tuniq. The thermal paste, that everybody would suggest is AS5. It's just an excellent paste for the money.
It isn't that hard to RAID 0. Just make sure you backup all your important files and information, because RAID 0 does have a downside to it. When and if a hard drive fails, you lose all the data between the two hard drives.