USB PC Fan Controller

As this is my first post I feel I should say how incredibly impressed I am with everyone here, you guys are inspirations!

That said, I have a burning question, so powerful that I find myself emerging from the shadows to inquire of you fine folks if what I am about to suggest may be done.

I want a Fan Controller for my PC project I am working on. I want it to plug into a USB port, and allow me to simply control Fan Speed (either through PWM, or simply raising and lowering voltages), but I want said control to be through a program I run on the desktop itself, not by some dial or automated temperature sensor system. Also it is worth noting that existing software solutions are inadequate, as my motherboard cannot support the number of fans my case will need.

I have been looking at Arduino and it seems that this could be a viable candidate, allowing me to tell it through the USB to either speed the fan up, or slow it down at my whim. However being new to this I am not sure if one could actually accomplish said task. It would need to control at least 2 fans, preferably more, and possibly allow fans to be grouped.

For a better idea of what I intend...

I am building a rather monstrous PC, the case will be themed and modded heavily, and potentially include a 7" LCD screen on the side. This screen will be hooked directly into the PC, thus anything I want it to display should be possible. My intent is to have it display a combination of system stats, and allow for things like control of fan speed etc... I have looked into every possible Fan Control device commercially available, and not a single one, no matter how expensive, currently in production will suit my needs either technically or aesthetically. I feel a small internal control device that will allow me to simply click a button with my mouse would be far more efficient and better fit the intended design parameters of my project. So far I have spent three months on the planning stage alone, and do not intend to begin the first phase of construction for at least another month, while I iron out the few remaining design issues I have.

Any help or information you guys can provide would be fantastic!