(i) If we lock old topics, users will create new topics, or worse, pollute unrelated topics. Personally I prefer the resurrection of old topics, that way the relevant information stays in one place.
(ii) We have dedicated Tiger and Leopard installation and post-installation forums.
I need to state a few things (my personal opinion/experience - not "official" InsanelyMac policy):
History will show that re-labeling forums and moving or locking old posts will not prevent lazy, uninformed or mentally challenged users from posting in the wrong place.
Even valid, up-to-date, known good (etc, etc) information can be used the wrong way, under any circumstances.
I don't think it's too much to expect that our users pay attention to the date and year of the topic they're reading - If someone should happen to kill their Mavericks installation by applying a solution that they found in a topic from 2008 then they were asking to learn the hard way.
When you are new to this community and have no idea where to begin, all of the information contained here, old and new, is confusing, potentially misleading even. As a newcomer you will still have to learn, all by yourself, how to separate what you can use from what you can't use. The only way to do that is to read, and that means you'll most likely be reading something (old or new) that may or may not apply to your situation, or may or may not be the best way to solve a particular problem. When you first come here, there is no way you can know that. Until you read some more, and then some more. That is a fact that no amount of archiving or rearranging can change.
I don't see that there is a way to ease the pain of those who don't like to read, after all we are dealing with a text-based medium here.
Think about this; if you take a step back and look at the requirements for installing and running OS X on a PC, they haven't changed much, if at all, since the early days. Most of our means to install OS X have improved over the years, but basic information found in topics from 2008 about property injection (still waiting for root device, ethernetbuiltin=y, gfxutil, DSDT, legacy kexts, IOKit, smbios), decryption (Appledecrypt, DSMOS, Fakesmc) and power management (...) is still true and therefore potentially useful to someone trying to see the big picture. Just read this blog post from 2008 by David F. Elliott to see what I mean, that information is the foundation for what we are doing, and it's still valid, five years later.