I'm not sure why techie or non techie should be different?

Anyway, at home here, I think it's more a matter of policy than need in terms of the old PC not being able to cope with the software on it.

We try to replace a PC after 4 years. The replacement is usually something near entry level (they have been Athlon dual cores for a while with 2GB RAM - although the motherboard bundle I got for the webserver had 4).

This policy seems fine for our Linux usage which does include updating to the newest version of the O/S within about a month of release.