Outside of power users like gamers, developers, CAD, Video editing, and other high end users a Pentium is more than good enough.
You are incorrect. At least on Windows 7, try to open a few tabs on a Netbook running an Atom processor, or a laptop/desktop running a Celeron or even a Core 2 processor and you will realize its going to behave like a fully loaded Geo Metro. Forget about running any HD content. May be they will work slightly better running XP or a variant of Linux.