I'll agree that the ram is overkill, but given the fact that you did state that he'd be ocing his system and that both i7 1156/1366 platforms overclock exceptionally well, I thought it might be a better idea to get some better ram depending on how fast you wanted to run the BLCK.
Yes, 1333mhz and 1600mhz ram comparisons show little difference (i7 1366 platform only officially supports 1066mhz spec according to intel anyway), but some 1600mhz kits are very close in price to some of the 1333mhz kits that you might as well get them instead especially when considering what sort of overclock you are aiming for.
In the case of the above for the X58 platform, triple channel ram provides slightly more bandwidth but the QPI bus is theoretically the main advantage. It gets around 20gb/s (assuming with 1333mhz ram), compared to the DMI interface which only gets 2gb/s, which is only 10% of X58's bandwidth. With today's cards, it might not make the biggest of differences, but scaling as you add more GPUs would theoretically be better on X58 then P55 (Having said that though, the PCI-E controller does help in compensating the lack of QPI).
To shortly summarize what I'm trying to say is that QPI may have better future potential and minimize bottlenecks today and when it comes to future GPUs when compared to Bloomfield. Simply because of the the bandwidth offered on X58's QPI, its one of the reasons we'll see a 6-core, 12threaded variant of Nehalem on it in future (not that everyone will need it, but it gives you an example of why intel is doing it, they've also said that 3 cores is enough to saturate the DMI bus)
While benchmarks do show that the both i5/i7 platforms have little differences among themselves, consider the fact that turbo mode on the 700 and 800 series chips is better then the implementation that is on the 900 chips, but this doesn't allow for fair clock for clock comparison. If anything, one might assume that it takes some higher clock speed ramping in order to beat Bloomfield based 920. If compared clock for clock in the here and now, we'd see some close results, but the i7 920 would still come out on top.
As for bottlenecks and overclocking, I'd have to disagree there. With more modern systems today the theory may not apply as much as it did back in the days of P4s, Athlons and when Core 2 first came out, but we can clearly get some decent boosts across the board (even say if the max fps count didn't go up, but the average went up slightly and the minimum rose significantly, we'd already have worthwhile gains).
If hes getting a sound card from you than that's okay. As long as its better then using realtek stuff (To be fair, onboard has come a long way but stills lacks in a few areas, especially annoying signal noise on analog).
As for my choice of case, the Antec 1200 is good (I use one myself), but does have its short comings (It can get cramped in there and the back panel where you route the cables through has limited clearance and will flex most of the time you put it with a nice cable job). Its also a bit noisy for my liking and the side panel window is a bit flimsy and can be easily scratched. Also, having to take apart the case just to clean dust filters is an annoyance when compared to some newer cases that have them external.
In regards to the 5970, it most likely has a modified PCI-E controller on it you'll find, so both GPUs should run at 16x bandwidth on the PCB (IIRC). It'll surely be a good card, but will supposedly be 13 inches long, so make sure you have a case with enough room to fit it.
As for monitors, I'll have no disagreement with you there. I myself am looking at moving to an IPS panel based screen when money allows me to do so.
The artic freezer 64 pro is starting to show its age, so that's why I'd recommend something better, especially if the machine is going into a room with a higher then average room temperature.