[Reach]

This will do it , and should run in your range. I just built something similar; a little higher end, but this is a nice rig.

processor: i5 2500 (no need to overclock this)
card: 560 ti will run BF3 maxed. If you prefer ATI, go with the 6870. For more power, go with a 570 or 6950, but keep in mind that they're more expensive.
ram: 4 gb ripjaws ddr3 1600. can probably find cheaper ram, but this is great stuff.
hd: 1 TB caviar blue
motherboard: ASUS P8P67
psu: Antec 520w gamer is fine.
some cheap case (I will personally recommend the antec 300 case. It's about $50-60 dollars and a really nice case! Lots of airflow, lots of space and it looks nice).
basic burner

Should run you 800 something total, depending on discounts, where you buy etc.

Honestly, this is pretty high end, given the only upgrades worth making are:

an OC on the 2500k processor, which isn't necessary (will require you buy a hyper 212+, combined with processor will run you another $50+ unnecessarily)
bumping up your card (gets expensive, and you won't need it for BF3)
doubling your ram (great, but not necessary)
getting expensive cases and or bigger drives, which you probably won't need.


I'd recommend my build exactly, which will rip Bf3 apart, but it runs closer to $1100. If you're only willing to spend 800, you'll have to settle at something around those specs above.