The best valued overclocking chip from Intel may actually turn out to be the 805D rather than the 955EE. It seems that the only difference between the 805D and the rest of the 8xx series are that the 805D couldn't run stable using with a 800MHz FSB. All the other features are still in place including EM64T, 2x1MB cache, and EIST downclocking to 1.86GHz. The great thing is they may actually be excellent overclockers with the limiting factor being how close you can get the FSB to 800MHz. HKEPC got the base FSB up from 133MHz to 185MHz for a 3.7GHz processor. Not bad for a $150 processor. Of course, it hasn't been released yet, but I thought the schedule was for the end of February.
http://www.hkepc.com/hwdb/pd-805-1.htm
For MadModMike, I know others have already said it, but the guide is great. I do have a suggestion for the Intel dual core recommendation though. Personally, I find the 8xx series a better value right now because Intel recently dropped their prices to clear inventory. The best value is the 830D which retails for $277.90 putting it at the same price level as the 920D.
http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=80831&affiliate=shopping
I know you recommended the 9xx series because they run cooler, but the power and temperature difference isn't that large right now because EIST support in the 9xx series is disabled preventing downclocking when idle.
I don't know if you want to mention steppings since it may to too complicated for an entry guide, but the preferred stepping for the 8xx series is of course the latest which is B0.
You have more experience with AMD than I do, so I really can't recommend anything for that section. I hope the moderators make this a sticky.