I switched in two 512mb modules from my dad's dual G4, and I honestly couldn't tell the difference in most things. Only way I noticed was a slightly higher frame rate in games that I wouldn't be able to notice anyway. I was in the same boat as you but I tried it out and I didn't feel the extra cost was justified. I think a lot of people feel that their comp is faster and it sounds better. Some people are probably just trying to justify the puchase to themselves to the point where they believe it is so much better. When I only try 256mb in my comp, I only notice it is slower when changing programs and frame rates, but not really too much. That is how dell can get away with using only 128MB of ram in their bottom systems, even with the integrated video memory taking up to 32MB of that 128.