I see your limited to Windows XP or RedHat V4.> http://www.ansoft.com/products/supported-operating-systems.cfm?product=hfss
But that is all I found for required Specs I would suggest you contact Ansoft to inquire about recommended hardware often design/cad programs have a list of recommended/preferred/required hardware such as video cards, ram and CPU's.
But that is all I found for required Specs I would suggest you contact Ansoft to inquire about recommended hardware often design/cad programs have a list of recommended/preferred/required hardware such as video cards, ram and CPU's.