The V8 works pretty well, but its expensive, other options like the Scythe Mugen Cooler or Xigmatech Dark Knight are just as good, but a lot cheaper.
Check www.frostytech.com for the top CPU coolers
You don't need to buy that much thermal paste, unless you plan on reapplying it often, smaller tubes are available for a lot less.
Unless you plan on doing some serious overclocking, the Classified board is a waste. That EVGA x3 SLI board is solid.
I would drop down to 6GB. You won't see any noticeable performance in games from the extra 6GB, consider the OCZ Gold kit, its a lot cheaper, and just as fast.
Those Velociraptors are noisy, and the new 7200rpm drives are almost as fast now. You could look into a SSD, Intel and OCZ are great choices. The Intel X25-M is very fast, but does have a hefty price tag (~$300).
The new Samsung Spinpoint F3 HDD are the fastest at the moment, and would be a good choice for your second HDD. If the RAID 1 array you are doing is just for backup, look into the Caviar Green line, they are low power drives.
That PSU is overkill for the system, you plan on doing SLI with the GTX275, so the Corsair 850TX would be ideal. Gives you more than enough power, and is a good deal cheaper. Additionally, the 850HX is modular if that is a concern.
Other than that, good choices, should make for a nice rig.