how to change the position of the center point of an object

Hi, I need to move the center point of a cube from the middle to the top left corner, then, when I want to rotate it, the object will rotate from that top left corner, my question is:

how to change this point from the center to the left corner?

regards

Select the position you want to be the origin with the 3d curser. To position it at a vertex, select the vertex then Shift+S / Curser to Selection then in object mode go to the Editing (F9) / Mesh panel and select the ‘Center Curser’ button. (In blender 2.5 for the last bit use Ctr;+Alt+Shift+C / Origin to 3d curser)
As you haven’t said which blender version you are using I’ll assume the latest stable release, blender 2.49b http://www.screencast.com/users/blenderwho/folders/Jing/media/07d07d75-894b-49c6-b10e-797b4df67c07

In Blender 2.5, the method you are telling isn’t working. Nothing happens even after doing it

Works for me om 2.54
http://www.screencast.com/users/blenderwho/folders/Jing/media/f3846a8c-6c70-4a21-b68d-53ce212ca28b