New to this: 5 Characters, 1 Box. What must I purchase?

[Ken]

I will be buying (for 4 clients):
- Quad core Intel Q6600
- 4GB RAM (initially I will buy 2GB, as this seems to be enough in Linux for now)
- 2 sata harddisks
- GeForce 8800

I already have a Samsung 226BW 22" widescreen, which has a good price/size/quality ratio.

Go with 4Gb of RAM straight off the bat rather than 2 (and I'd also suggest going for 2x2 rather than 4x1 just in case you still want to expand in the future), main reason being that under windows each instance of WoW takes about 450Mb of ram so even with only 4 clients you'll be very very close to the swap limit right away (aand perhaps over depending on what you are running as services and how much ram WinE takes up while running). RAM is cheap enough compared to everything else at the moment that the extra 2Gb shouldn't add much to your build cost.

Thanks for the tip, but I don't have that memory problem, because I'm running Linux. Each WoW instance takes about 200-300MB and my operating system (including the Gnome - the graphical frontend - takes about 120MB). Memory usage will rise when I go to Shattrath of course, but I don't have that problem yet.
I will indeed buy 1x 2GB for easier future expansion, another good tip, thanks.
I'd rather save some costs with RAM so I can have a better graphics card. Good RAM isn't cheap these days (the 1000MHz+ stuff). Only old PC800 is cheap, but that's too slow for these CPU's.