Bah. Min would be roughly 2.0 Ghz, 128 mb video ram, 512 DDR RAM.
RTS have the reputation to be ressource whores. Well you can always play at low settings but IMO in an RTS, it sort of sucks.
But I disgress, this is too early to talk about system requirement as we have no idea how many units will be on the map at the same time.