i'm a big ole dummy, and i need some help, quick. i'm taking my sister out to get her an emac this morning, and i thought i might get myself some extra ram while i'm at it. so i started researching, and i can't even figure out exactly what it is i need. i have an 800mhz 15" fp g4 iMac w/superdrive, preinstalled 256 mb ram (the original top of the line model). what do i need in extra ram, and where's the best place to go? thanks.