Get an i7 cpu and maybe a better gpu.
The game is said to need a quad core cpu to get good performace from battlefield 3.
I saw some of the recommend specs, but can't find them again. I think they were:
1) Quad core CPU
2) 1GB ATI or Nvidia card
3) 4GB of ddr3 ram
4) direct x11
5) 10GB HD
6) windows7 64 bit
7) 1440x900 or better
I don't know if it's right or not, but I just want to give a heads up if it's right.