Agreed with Kubica. While I've never used the FCP groton Chinese parts, I have not heard anything good. I just replaced my arms and chose to use original Lemforder arms. BimmerWorld had the best price right now on these at $195 an arm if my memory is correct. Add another $65 for the OE bushing set and try to reuse the inner ball joints and you should be good to go.
Also look at doing the rear trailing arm bushings soon. Then you will have a razor sharp crisp handling XI.
Trust me, the XI with a fresh suspension setup handles phenomenally!!!! I have H&R coilovers on mine and with fresh bushings and control arms and 18" rims with summer sport tires, she is on RAILS. Flat as a board through the corners and lots of grip.
I am reluctant to admit it....but I feel more confortable in my XI pushing hard into corners than I do in my E46 M3.