I was thinking about cutting costs if people wanted to come over and play PC games. Well... Cutting costs to the best I can

I was thinking about buying a mondo high-end PC, and splitting it into 4 (I know it can be done with Linux, no idea bout Vista or XP though, prefer Vista)
Basically I was going to buy a single new PC where if I play alone it's got all the juice I need, and with friends it'll have enough power to run up to 4 player LAN(ish). I dont know if it can be done with one PC to an acceptable level but Here's what I was lookin at for my next tax return:

Core 2 Quad Q6600 (or higher quad core)
4GB PC9500 DDR2 RAM (or 8GB if I go 64 bit and enough games are 64-bit capable)
2x GeForce 9800GX2 in Quad-SLi (essentially an 8800GT video card per... user?)
and 2 Raptor 10,000 RPM Harddrives in Raid 0 (or 4 if that needs to be there).

All in all it'd cost me roughly $2200 for the hardware alone. Then I'd buy 4 monitors (probably just 20" wide each), and 4 identical sets of keyboards and mice. so that'd run me up to about $3200 (OUCH), and with one tower it'd save me alot of room, especially if I went wireless.

Now I know Linux has a utility that allows you to essentially split a PC into up to 8 terminals, but every time I try to search for something like this for Windows, all I get is virtual desktops that you can switch between users, but two people cant do two different things at the same time with different keyboard/mice or monitors as you can with the Linux util. Is there anything out there like this for Vista? And is this project even feasible? Will it just try to run all 4 gfx cards on one one gaming terminal and leave the rest to deal with half-assed integrated or can I say "hey, this guy gets this core and GPU, this guy gets this core and GPU", etc. I know Crysis is 64-bit capable but not many of my friends even like Crysis. They prefer CSS, WoW, or strategy games. I've read that the GFX performance slows down tremendously when trying this but it was written back in the AGP GeForce FX/ Radeon 9000 era. Now with the advent of dual, tri and quad SLI/Crossfire, is this an issue?

And of course I can always cut costs even more by going ATi, and going 2 users instead of trying for four (dropping the price down to roughly uhhh... $1500?) , I'mma stick with the Q6600 though simply because it can be had for $230, and with two users (again if this can be done) thats 2 cores each.

Thank you tech-gurus!

I know about KVM switches that allow you to use one mouse/keyboard/monitor on two different towers. I know of 'vitrual desktops' that allow you to install different OS in a "safe zone" on your computer. But I've never heard of what you are looking for.

No.... scratch that. I remember seeing something in a SkyMall magazine while I was waiting for a flight to take off that allows you to use one tower and have multiple "computers" in that tower to share with other people. But, I can't remember the name of the product.

But, to burst your bubble, unless you plan on like playing "older" games like Diablo II and stuff, I doubt that one GPU or even a GPU in SLI will be able to handle 4 different people playing games...

I think the aforementioned product was for a university/college environment where you would only be using Office suites and Internet stuff....

yeah, I thought so. I found that program (cant remember the name) and one of its limitations is the graphics. It can split cores and memory but I dont think it can split graphics power. It's a program built specifically for schools so they can cut costs by having one tower power up to 8 "computers" or terminals. I was hoping having 4 separate GPU's would work but I dont think there's anything out there that will allow assigning specific parts to specific terminals. Maybe someone will build one someday