All in all a good writeup, but there was a few things I reacted on..
First, regarding CPU : "Nvidia cards draw their power greatly on the processor and thus generate extra load. ATI cards operate at maximum speed pretty much independent of the processor." - This sounds like a complete load of bollocks, and a quick google search did not reveal any proof of this. Do you have any links that confirms this?
Second ->"Always go for a hardware raid with a raidcontroller pci,pcie or onboard (=built-in in the motherboard)"
*BEEP*, wrong. 99% of cheap (think sub-1000$) raid cards, and mobo raids are so-called
"Fake RAID"s, and does NOT give any hardware acceleration, but does all through drivers (in other words, using your cpu, that should be using all its electrons on running the game). Many of those drivers also perform rather poorly compared to other software raids. In some cases, a pure software raid gives much better performance.
Also, as a general tip, it's good to have the OS on one disk / raid, and the data/game on another disk / raid. That way system I/O won't block game I/O and vice versa (especially swap file).
Oh, and another thing. I play the game with a card with 256mb ram, and it works fine. Some textures are slow to load, but that doesn't cause any slowdown on the game.
One other thing, when it comes to 64bit and ram, if windows don't see all the installed ram, check
http://support.microsoft.com/kb/929605
Regarding the graphics settings, because of my old gfx card (7800GT 256mb) I did a lot of testing and tweaking to get it to run well AND look decent / useful. I won't write a guide about it (not now at least), but I did take screenshots of my current settings, and a few "showcase" screenshots. With these settings I usually get as good or better FPS than Low settings, but IMO it looks way better (and you can see into the distance).
Screenshots :
http://thelazy.net/gallery2/v/games/aoc/graphics/