Hi! I just bought my 12'' PB with 256MN a week ago and wanted to put more memory in it. The only problem is that i don't know how much I need. I use iTunes, Word, PowerPoint, Excel, GarageBand, Safari, and iChat. The PowerBook is already pretty quick and apps don't take too long to open but I would like to make it really quick. What should I do and where should I buy it? Thanks.