First, make sure that you have downloaded the latest version of Adobe Acrobat Reader.
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Important note: Remember where you saved the file. You will need to run this file in the next few steps.

Once your download is done and you are ready to go, follow these instructions to install Adobe Acrobat Reader:

Exit all programs and locate the file that you just downloaded. Double-Click the file, this will start the installation process. Wait for the file to Unpack itself. Click Yes IF it informs you about any uninstall information (May or may not show up) At the dialog box reading "Acrobat Reader 5.1 Setup", click Next. Accept any license agreements (May or may not be required for some installations). At the window labeled "Choose Destination Location", click Next. Wait for the installation process to complete. Click Finish. Your computer will restart itself. Acrobat Reader 5.1 Installation is now complete.