What you asking for is more related to hardware than operating system software. Consider that you are asking the computer to output one large resolution rather than two synchronized resolutions. Therefore, the feature is largely dependent on what type of graphics accelerator is present. In the case of a Windows 7 desktop workstation with an AMD "Eyefinity" compatible discrete GPU, one could display a single desktop on multiple monitors. Nvidia provides similar technology.
Windows is only as powerful as the hardware in which it runs. :smile: