I only have room in my home workspace for a 20" iMac. I notice there are additional options for processor, etc. on the 24". For home use, but wanting to stay ahead of the curve for next 3 years, is there a disadvantage in fewer configuration options on the 20"? It seems the 24" has an optional graphics card that with the 2.93 processor might run Snow Leopard faster. Am I at a disadvantage sticking with the 20"? On the 20" I would get the 4 of ram vs. 2. Thanks