First off, see how well your computer can run the game by doing this:
1). Go to
www.srtest.com2). Select Battlefield 3 by either going to the dropdown box or typing it in. Click [Can You Run It?]
2a). You may need to install the srtest file. Download it.
3). The process will take a short bit as it analyzes your computer.
4). I would recommend only getting the game if the meter meets or passes the minimal requirements.