There are several different Graphical presets - Low, Medium, High, Ultra and Custom.
This article tells you about the different presets and shows you what they look like:
http://www.bit-tech.net/hardware/2011/11/10/battlefield-3-technical-analysis/1
The two most demanding graphical settings are:
1) Anti-aliasing Deferred - Disabled/2xMSAA/4xMSAA
2) Ambient Occlusion - Disabled/SSAO/HBAO
4xMSAA will pretty much cut your framerate down by a 1/3rd, but will make the game look so much better as it eliminates all the the jagged edges and moving pixels you see on the edge of straight textures.
HBAO is the most resource heavy Ambient Occlusion setting. It adds a new level of shadows to the scene, usually where two objects meet and adds a good amount of depth to the scene.
I advise using the Custom preset, setting everything to High and enabling 4xMSAA and SSAO, and using 16x Anisotropic Filtering - this should give you a great looking game whilst staying above 60fps 95%+ of the time.