better look elsewhere and increase your budge. get an intel quad core if you want to play bf3 with anything near smooth fps. also look at a minimum of a gtx 270,gtx 450,gtx 550 or similar performing ati cards.
the fx 4100 is a dual core cpu in real terms. yes it has 4 cpus but there paired into modules. so they are comparable to a dualcore cpu with hyperthreading. which will be no good for bf3. you will get little more real world perfomance than the old 775 dualcores. so a pointless buy for bf3.
to play bf3 the minimum you need is a 775 quad core of 2.4 or faster
or a amd am2 quad core of 2.6 or faster.
4 gigs of ddr2 800 or faster.
a gtx 260 or ati 4890 or faster.
if you pick nvidia you want a minimum of a (x50 1s you get past the gtx 260) x60 x70 or x80 x90
for ati you need to get a x750 x760 x870 x690 perfereably the higher the fist number x the better for the lower numbers preferably 6 or better.