That is going to be a fast rig, no doubt. There is one piece of advice that a few people gave you that I really dont understand however. If people complain that the 74gb raptor isn't worth the price/performance/storage ratio, why would they suggest a drive that makes that ratio EVEN WORSE? The 36gb model not only has half of the storage, but also takes a significant performance hit. It's specs are not nearly as impressive. On top of that, its only a 40-60 dollar price difference, and you clearly aren't splitting hairs when it comes to financing this build. Personally, I believe that the 36gb model isn't ever worth it, whereas if you have the money, the 74gb model definitely is. I think these guys are just used to advising people making $800-1500 computers that raptors aren't worth it and are too stubborn to change their opinions as the situation permits.
One of the most common ways people try to downplay the raptor is by using the arguement that "yea, its faster, but only in a very few situations." That is a load of pure, grade A Bull. Every single time your computer acceses the hard drive the raptor will do it quicker than a conventional 7200rpm drive, and guess what? Your HDD is accessed far more often than 90% of people seem to think (or perhaps, care to admit?).
In my opinion, the best non-raptor drives are the monstrous 300-400 drives with 16mb cache. They give the best of both worlds, gobs of storage, and performance approaching raptor territory.
Spending as much as you are on the computer, I think you would be doing yourself (and your son) a huge discredit by going with the 36gb model. The 74gb has plenty of storage to store many games, especially if you dont fill it up with games with really low system requirements.
Yes, but no sprinkles. For every sprinkle i find, i shall KILL you.