Or you can always go for broke (literally) and register for 100 years with Network Solutions.
As Ken says, don't confuse cause and effect. Older domains will typically rank well because they've had time to build up more incoming links and develop more (presumably valuable) content.
But that doesn't mean a brand-new domain that was just registered for a multi-year term will get any kind of boost in the SE rankings simply
because of having been registered for a multi-year term.
Given how cheap multi-year domain registration is (unless you're registering for 100 years at a pop
) I can't see how the SEs would reasonably give any significant weight to the length of registration term. If
it carries weight, it's almost certainly got to be very
slight at best.
Not sure how anyone would be able to prove it one way or the other, though.