Instructions
Visit the "GTA: San Andreas" homepage via the Rockstar Games website.
Scroll down to the bottom of the homepage and click "Click Here for PC Version Info &Media."
Click "Buy Now" to purchase the full version of the game.
Select a store for purchasing the game, Among the options are Amazon, Game, Gamestation and EB Games. Purchase the game by providing your credit card number. Some websites accept PayPal as well.
Download the game to your PC. The download link may be emailed to you. On some websites, the link will be accessible after you log in to the user portal offered by the online store.
Double-click the setup file after the download completes. Follow the on-screen instructions and wait for the game to finish installing to your PC.