I'm glad I was able to download your article. I tried from your blog - it downloads something, but I couldn't open it. I was able to open the one linked above in this forum.
How quickly does this information change? How often does one have to re-evaluate the relative consumption of various classes of computer (laptop vs. desktop etc.)?
The broken link is because homepower.com removed the pdf from their downloadables; it's been changed to point to the copy on the SPCR server.
As to how often... that's not easy to answer. It depends how uptodate you want to be -- and how many different types of computers you want to keep on top of.
The article I wrote was already somewhat outdated by the time it was published, that's due to the slow process of print magazine publishing and the speed of CPU development, for the latter, especially over the past year or so.
In general, there is greater focus on energy efficiency in the industry, so you might expect continuing improvements. On the other hand, mobility is driven by the need to conserve battery power and maximize run time, needs that don't exist for desktops in general, so I'd expect a gap to remain between the two general classes -- until/unless the 2 classes merge fully. That process is happening, but I doubt it will be complete for some years yet, if ever. There may always be a need for big PCs that have higher capacity for components & connections.
The other thing is that the energy consumption of a PC during its operational life is only 20-25% of its total. Around 75% of the energy it uses occurs during the production stage. This is because the "energy density" of CPUs, IC chips and other electronics and IT gear (hard disk, memory, etc) is very high.
A typical desktop PC (with monitor) requires 240kg of fossil fuels to produce; its total weight might be 20kg, so each kg in a computer requires 12kg of fossil fuels. A typical car requires 2000kg; typical weight is around 1000kg, so each kg in a car requires only 2kg of fossil fuels.
Even if you decrease its electricity consumption by half, the total energy consumption represented by a computer would only drop by maybe 12~15%. Not insignificant, but a 50% reduction in average power consumption would be VERY difficult to achieve with tweaks and adjustments to an existing computer; you'd just have to go to a newer, more minimalist computer with higher efficiency parts to start with -- but then you're financing another computer whose manufacture requires 7-8 times the energy you'll save.
Hopefully, that addresses your question somewhat?