It’s up to you. Once is use my laptop, which has 1.6 Ghz Dual core cpu, 2GB of RAM, and HD Graphics 4000 (run quite good for building small airport, forget about this ). Though beware, since the game is very heavy, especially to your CPU. Or you could just buy the game now, saves some money to buy a new one (the game is cheaper now than later)
But, once again, it’s up to you.