This is from EA's Site
Minimum requirements for Battlefield 3
•OS: Windows Vista or Windows 7
•Processor: Core 2 Duo @ 2.0GHz
•RAM: 2GB
•Graphic card: DirectX 10 or 11 compatible Nvidia or AMD ATI card.
•Graphics card memory: 512 MB
•Hard drive: 15 GB for disc version or 10 GB for digital version
Take note this is minimum, so you'll be able to play on low. Give specifics on your gfx card.
what you should get is:
a gfx card with atleast 1 gig of ram
atleast 8 ram (your going to need it especially with all of these higher end games coming out.)
You should do an overhaul with RAM, and grab an Intel i5 or i7.