If the HP is the better rig i would say that one, however, it all depends on what motherboard it has for available PCI express cards as most are today. Also, internal size of the case as alot of new graphics cards are mahooosive!! which also leads to the next question, power supply. My graphics card needs its own 500watts of power with 3 connectors!

However, the choices are limitless cards wise, its just knowning what the rig can take.