AFAIK, but I'm not certain, since Xeons are designed to work in tandem as a pair (or even 4 or more) on one motherboard, I think (again, not certain) that using only a single Xeon in one board will partially cripple it, at least you'll experience bottlenecks. They're designed to work in pairs basically, unlike "consumer" chips like the equivalent i7 etc.
At any rate your best bet would be to sell it and get a regular consumer chip. You'll probably find that a consumer chip at roughly the same speed will be a little quicker. The alternative would be to do it properly and buy a second identical matching Xeon and you're good to go. But you're talking MAJOR expense there, including (even if you go with option 1) an expensive Xeon board. You're also probably looking at having to buy ECC RAM too.
Basically it's not worth it. Sell it
Actually, thinking about it, I'm not sure if you could even run one Xeon... Too much hassle to make it worthwhile in my experience. I'm running a small farm of dual xeon machines here and they're awesome but I get the same speed from each with my single 6-core i7 machine, and it cost half as much... you see where I'm going