I use a P-III and Athlon 64, with loads of storage and the latest graphics cards- My Athlon uses an NVidia GeForce- an excellent investment if you are serious about rendering... Anyone who thinks 23 minutes is "too long" to do a complex architecture render in HDRI hasn't done something like this before. Sure- more expensive 3D software can do it faster, but I use several machines- so I can use another one while one is rendering. If I want really hi-rez- like 4072 x 4072, I let it render overnight. Eat diner, drink some wine, watch TV- lots of things to do while stuff renders!