I have a Windows machine running an i7 processor that supports up to 4 graphics cards. I want to find a solution where I can connect 4 keyboards and mouse and make 3 maybe 4 separate machines for office use. We basically have to use word and Dreamweaver with a little browsing. Is there any solution, hardware or software, for this?
You can do this with Windows MultiPoint Server, provided you have the appropriate volume licensing. You can also purchase a machine from an OEM, but I'm guessing you want to keep your existing computer rather than purchase one.
Windows MultiPoint Server http://www.microsoft.com/windows/multipoint/default.aspx
A hardware option would be something from NComputing (http://www.ncomputing.com/).
First off, the plural of mouse is mice.
Second, your title says 2, but your description says 4 keyboards. (consistency!)
Third, you sure did ask a mouthful
Simply put, no this is not possible on any Windows platform. This is both a limitation of licensing and technological programming.
The only realistic way you can do this is in Linux, it is called Hot-Seating or a Hydra system. If you want an easy solution that costs a bit of money check out userful at: http://www2.userful.com/products/userful-multiseat-linux
The reality is that you can do this with any distribution of Linux FOR FREE, but to build it from scratch (ala, not using userful software) you will need to get dirty in X11 with X11 programming.
Now I'm actually in the stage of learning how to do this, so I can't guide you to do it manually. Even if I could, the process is so complex I would not guide you here how to do it.