Are these desktops good for gaming?

2nd system is far better because it was AMD who invented 64 bit processor for the first time in IT industry. Due to impressive cooling system, its performance will remain smooth even at higher room temperatures in hot areas or in summer season. But would recommend you to buy Seagate fat hard drive, Seagate is more reliable brand. And first confirm that your 1 GB Graphics Card has its own dedicated RAM i.e it will not share the resources of RAMs on your motherboard.