Gotcha on the RAM matching. What's the purpose of that?
Each channel of RAM can be accessed simultaneously, increasing throughput. It's much the same idea as putting multiple disk drives in a RAID0.
I may have conflicted myself in spec'ing out 64-bit and also a 10k rpm drive though, as the higher speed is a bandaid for a problem on 32-bit systems. Oh well.
No, no conflict. I highly recommend getting the fastest possible hard drive you can reasonably afford for your primary drive. For a huge number (probably the majority) of common tasks, the speed of access to your primary drive has an impact. So a fast primary drive can be one of the most significant factors in your perceived system performance.
SSD's are great, with the best performance, but a bit pricey still. Velociraptors are pretty popular right now. But the new SATA 6Gb/s stuff is coming on strong, as well.
As for the SSD + SATA 6GB/s combo: You don't really need a fast data drive if you are using a server, only if you are storing data locally on your computer. For most companies, all the data pretty much stays on a server, so a data drive on a workstation is rather unnecessary. It depends on your needs. But the SSD/SATA combo can work well if you need a local data drive.
And as a technical point, the SATA consortium is trying to keep people from using the term "SATA III". The main problem is that it is too easy to confuse "SATA III" with "SATA 3Gb/s", aka "SATA II". So they're trying to get everyone to use the term "SATA 6Gb/s" instead of "SATA III".