enough memory

help settle a discussion. A friend got a new laptop. I am not good with laptop's so I may be wrong here. But if its the same as a desktop, its something I have researched in the past. His new LT has 512 MBR. I tried to tell him that was plenty. He does not believe me. He wants to double it. No big deal, its his $. I say it all depends on what you do with the PC. If you play a lot of games, do movie editing, watch movies while online burning CD's and listening to realplayer, all at the same time, well, yes, you need more memory. But this is not the case. He plays no games, doesnt edit music or movies. Not using CAD. Basicly surfs online and uses office very little.
Might listen to some tunes on media player. He saw that a lot of resources were being used. Well, XP itself eats mem and resources. I told him that was the norm.
I learned to use system monitor to see how much mem was used and to see if my virtual mem, swap file was getting used. And think he should do that and save some $.
What is anyones opinion?
thanks
B

peace be with you