1) If you're not overclocking, why are you buying DDR2-800? Stock speed for RAM on your E6600 is DDR2-533. Even Kingston DDR2-667 is really cheap. 1GB sticks are the sweet spot; 2GB are notably more expensive per GB.
Skip RAID altogether unless you plan on buying a real RAID controller for a RAID5 array. For mission-critical machines, a single drive with regular backups is a better idea.
Raptors are noisy; why bother buying a 'quiet' Zalman CPU cooler? SE16s are very fast; I'd skip the Raptors altogether.