Adobe Acrobat and Reader 8 introduces a new feature called graphical processing unit (GPU) acceleration. This features enhances page display, zooming, and panning within PDF files. When Acrobat or Adobe Reader starts, it detects the properties of the video card and enables the Use 2D GPU Acceleration feature within Acrobat or Adobe Reader. The 2D GPU acceleration check box will only be visible if Acrobat or Adobe Reader detects a supported video card.
This should pose a very good reason to upgrade your current version of Adobe Reader if your videocard is capable of Shader Model 3.0. Also, Nvidia has posted an article detailing further the advantages brought by the new version of Reader.