I am sure I don't need it right now, but I plan on using it for the next 4 or 5 years, and I don't know if I may regret the decision in a couple of months or years.
OK I get that but go ahead and read that ArsTechnica article, it's pretty descriptive. Unless you'll be doing AV stuff profesionally, it's a waste of $$$.
It really depends but if you even don't know what hyperthreading is, that means you even haven't got into these things seriously (no offense).
Also I am pretty sure hyper threading won't be "mandatory" for future OS releases or applications, it's been around few years and developers haven't put much effort in using this technology (well apart from those pro applications). Just go ahead and ask any gamers (most of them run i5s or even i3s). i7 is aimed at niche market really, a bit wider than Xeons but still...
On the other hand, since you'll be spending so much money I guess getting i7 isn't really that big of a deal.