Gone West's first summary is correct. But I would just mention one additional point, since you seem to have been 'dabbling' at it a little since May 2000.
Superbly able as you may be on a jet, and even if you are totally OK in a light plane, there is also the "90 day rule". This requires that you have carried out, as "sole manipulator of the flying controls", 3 take offs and 3 landings within the preceding 90 days if you intend to take PASSENGERS while you act as Pilot in Command of the light plane class. Miss the 90 days, and you'd have to achieve your 3 t/o and landings solo before legally, and insurably, taking passengers for your occassional jollies.
So yes, Instructor and Proficiency Check are always the other way to do it.