I own a 12" Powerbook G4 1.33GHz In my system profiler (sorry kind of a newb to Macs) it says I have a total of 512mb of RAM. Says: DIMM0/Built-In - 256mb Speed: Built-In DIMM1/J31 - 256mb DDR SDRAM Speed: PC2700U-25330 So does this mean I have an open slot still? From what I read in some searches my PB has 2 slots for RAM cards and 256mb built in to the Logic Board (again sorry, Mac newb) already? I want to upgrade to as much RAM as possible for my little PB. (Getting used to the squinting, now just want to get rid of the lag when using programs like Photoshop and iphoto with my 7000+ photos) So whats the max I can get installed? and what kind of compatable card(s) would I have to purchase to acheive this w/o some of the issues and problems I see occur when upgrading RAM..? Thanks for any info..