Late reply but it might be helpful for you or someone else searching for this.
For PC specs, based from both my own testing and computer knowledge. Mods might impact these requirements.
Anything as fast as the following specs or faster will suffice in most cases.
CPU: Intel Core 2 Quad Q6600 2.6GHz or better
RAM: 4GB (Minimum DDR2 800MHz+)
DISK: 7200RPM HDD or an SSD (Heavily recommend using SSD if you got one).
GPU: Should work with even integrated graphics, since hosting is CPU/RAM/DISK reliant.
So the short explanation would be:
Basically any average PC newer 2007 will suffice.