an i7 2600k can be much more powerful since it can be oc'd waaaayyyy more. it is also a lot cheaper.
the x2 is kind of not worth it. for its giant price you can get a couple of these (really vertex 3's, and dont mind the bad reviews they fixed the problems)- http://www.newegg.com/Product/Product.aspx?Item=N82E16820233181&cm_re=corsair_force_3-_-20-233-181-_-Product
also newegg reviewers are idiots
He's running VMs and doing things besides gaming. For gaming both of these CPUs are more than sufficient. For VM and parallel processing the 970 destroys the 2600.
The i7-970 is not unlocked, it's multiplier has to stay within spec. It can still be overclocked with the BCLK alone.