I just started my multiboxing project last week. Started with the following:

- Quad-Core CPU (Core Q9450)
- Vista x64
- 4 GB RAM
- 8800 GTX
- 20" monitor + 24" monitor (1920x1200)
- keyclone (well worth the money, considering how much the hardware costs )
- just one WoW installation (you maybe could use another one for the main if you use two monitors)

I think you could play this with five accounts, I started with three (main on the 20", 24" in pivot mode). Switched to four accounts, tried to just use the 24" monitor, but 960x600 for each account just isn't enough. Soooo, added this:

- 30" monitor (Dell 3008WFP, IQ-wise way better than the Dell 2407WFP I had) (2560x1600)

Some numbers: 2560x1600 are 77% more pixels than 1920x1200, 30" is 56% more area than 24". So it has finer pixels. I like that. Remember: A Macbook crams even more pixels per area onto its display. And has the same resolution (1280x800) each account has with my setup, by the way.

This is really nice for a quad-setup without using an additional monitor for the main. Yeah, if I already play four accounts, why not five, I know. I guess I would just split the screen differently with five account (upper half of the screen 3x 853x800, I guess that would work, even though it's a weird aspect ratio). It's quite comfortable not to have an additional monitor. And surprisingly, the 8800 GTX can handle it fine, with everything maxed and 2x FSAA.

But yesterday another problem cropped up: 4 GB is not enough! At least not with Vista x64 and if you have much stuff running in the background. 4x WoW with some addons = 2.5 GB, OS + stuff = 1 GB or more... so now it's 8 GB and I'm happy.

The only problem I see with five accounts is that you either have to use one CPU core for two WoW instances. Or you split four instances over three cores. But Intel's new Quads should handle that just fine I guess.