I must admit I pretty much guessed the results fairly accurately at the beginning of the article, but it's nice to see someone actually put in the legwork and do some serious testing.
When one of my users complains of performance issues the first thing I do is look at how much RAM they have in their system, but immediately afterwards, I clean the startup list and defrag the hard disk. Defragging can have truly dramatic results. Also, upgrading to a faster hard drive (more cache, lower seek times) can do wonders.
The biggest job out of these is actually defragging, as it is the most time consuming. Requiring manual initiation, often requiring many passes, and frequently needing some space freeing up to get the job done properly.
Because of this, it is infrequently done in XP, which exacerbates the problem. (as I write this I am currently remoted into 3 separate desktops running updates and defrags after migrating them to a new domain) This is entirely because of politics, as previous versions of windows could indeed have defrag scheduled automatically.
MS bought the defrag technology from Executive Software, from their flagship product Diskeeper. Because of this, Executive Software retained the rights to core components such as the scheduling agent, and the boot-time defrag which could process normally locked system files such as the pagefile and the registry files.
Thankfully, this has changed post-Vista. Not only can defrag be scheduled again, but the windows scheduling agent has been given a steroid injection (seriously, if you've got a vista or 7 machine knocking around, and you've not seen it yet, have a look in computer management, it's very powerful).
Of course, from a sysadmins point of view, the scheduling can all be governed from group policy management on the server, so you can dictate whether your domain machines perform a defrag at a given time, or on a given trigger, such as the computer becoming idle.
I'm not saying this is THE critical update that we've all been waiting for, but any sysadmin will tell you, after a couple of years of neglect, that hard drive becomes fragged to the point where a reinstall can require fewer man hours.