To anyone here who has a new 13" aluminum MacBook at their fingertips: Please post the Build # of the version of 10.5.5 that came pre-installed on your MacBook. Also, please mention whether you have the 2.0 GHz or the 2.4 GHz model. Thanks! To locate build number, follow this easy three-step process: 1) Click on the "" on the top left corner of your monitor. 2) Click on "About This Mac" 3) Move the arrow directly over the text that reads "Version 10.5.5" and then click once. As soon as you perform step 3, the Build number should be displayed in the exact same location as your arrow.