OS: Windows 7 SP1+, 8, 10; Mac OS X 10.8+.Windows XP & Vista are not supported; and server versions of Windows & OS X are not tested.
GPU: Graphics card with DX9 (shader model 2.0) capabilities. Anything made since 2004 should work.
If you are planning to make a game which is more intensive then Unity will be able to support anything up to the most spec'ed out hardware. It will be possible to tailor your games for your hardware capabilities.