Are upgrades viable?

In an article: Choosing an upgrade path from Windows 98 the author describes how to:

...give a new lease on life to aging laptops and PCs by replacing obsolete OSes such as Windows 98 with a combination of Linux, free open source applications, and inexpensive commercial software.


OK, good idea. But how viable is this in practice? The argument goes that they aren't good enough to run Windows XP, but make brilliant machines to run Linux.

Frankly, I don't see this working. My experience of all modern desktop environments and applications is that they're bloated with significant memory and CPU requirements. We're talking about using applications like openoffice, crossover office, KDE, Gnome - and I wouldn't want to run any of them on an ancient machine.

As I see it, new hardware (or even nearly new) is dirt cheap, and the cost of making the old stuff work, and supporting it, and the time lost due to it being slower than a new machine, makes the idea of trying to re-use old machines financially unattractive.