Being able to use the three screens as one large display is a function of the video card (ATI Eyefinity, or NVIDIA Surround), but if you just want to have the three monitors rotated to Portrait and use them as extended desktops, you can do this using the Windows Screen Resolution settings, or the DisplayFusion Monitor Configuration feature.

You can give it a try by grabbing a 30-day trial key here: http://www.displayfusion.com/Trial

Please let me know if you have any other questions.

Thanks!