Summary from an article on the difference between i5 and i7.

Overall, the new Core i5 processors are far more evolutionary than revolutionary. While these new processors are actually quite a bit different from the Core i7 processors currently available, many features, such as the enhanced turbo boost and dual-channel memory, are shared with new Core i7 processors. The difference between Core i5 and Core i7, then, will be somewhat dependent on which particular Core i7 one is comparing Core i5 to.
Even so, Core i5 is clearly meant to be a more mainstream processor. Those who use their computers for heavily multi-thread applications will miss hyper-threading and the triple-channel memory, which means that a Core i7 on an LGA1366 socket will be best. For most us, however, Core i5 is more cost effective (it's available around $200), and quite adequate for our needs.

Rest of the article- http://www.brighthub.com/computing/h...les/48391.aspx

I think single box multiboxing would probably fall into the power user class.