you should be able to run it fine on medium as the pc is the lead platform the recommended requirements may be slightly higher. minimum recommended will likely to be a dual core @3ghz and an 88gt. or there abouts.
Lets all pray they don't pull a Crytek and really do keep the PC as the lead platform. I just have a sinking feeling BF3 will be consolzied beyond belief. What financial incentive would a developer have to make the PC the lead platform when they can make tons of $$$ selling a sub par console turd. (Black Ops, Crysis 2).
I do really hope it runs well on a PC, but if you have hardware equal to or better than a console you should be fine. Just look at Crysis 2, its not breaking any new graphics territory.