It is a tertiary concern, to be honest, after performance and cost.  That isn't to say that if a greener option exists and up front cost is marginally higher, we wouldn't still go with it.  There may be tax advantages that offset some  of the increased acquisition cost, and cost over lifetime may actually be less with a greener option.  Also, "green" can mean different things, from the method of manufacture to increased efficiency.  Lower power consumption is a benefit to both the user and the environment, but if the acquisition cost is excessive enough to significantly shift our ROI, we would be hard pressed to justify the expense.  There is the other end of the life cycle as well, and it takes only slight effort to dispose of obsolete equipment in a eco-friendly manner, and in many cases local/state regulations govern electronics disposal anyway.  I suppose it is like most individuals to be really honest; we are willing to make an effort to be green, as long as the cost and effort required isn't too high.