your computer will most likely be plug n play. in addition, your SATA II HDD will be compatible with SATA III w/o a hitch. all you need to do is, tells the bios with drive to boot from, whether it will be the SSD or HDD.
from my experience. i would back up my old HDD information, then back it up, the format the drive. put your BF3 on to you SSD and go from there