There's always something new coming out....May as well wait forever.
True, though when it comes to a motherboard and PC now is one of the worst times to upgrade, with new platforms on the horizon from both Intel and AMD.
So, in essence:
That's the easiest solution to all your problems? Bull****. Its like burning down your house and rebuilding because you've discovered multiple leaks in your roof and your guests keep complaining about it. Formatting isn't the solution in many cases, its just a lazy-ass way for IT techies to fix problems they have no business trying to fix in the first place because they're not skilled enough. And all it does is create more problems for the techies who have to fix the problem these users have that followed the advice to format, didn't back up, and now complain that they lost all their data (read: photos, music, and porn).
Formatting in many cases is the quickest solution, especially on systems that haven't had a good cleanup in a while. Jmak summed it up quite nicely, though I'll see if I can build on this. Given an extremely "dirty" installation, I'm willing to put forward that a backup followed by a fresh install of windows, drivers, applications and updates won't take much longer than "cleaning up the PC", and will result in a far greater performance boost that remain noticeable for longer.
Is it the easiest solution? Possibly. Quickest? Also possible. Yields a larger performance increase when compared to a manual system cleanup? Most definitely.
I find that the quickest ways of speeding up a PC are:
1) Run a registry cleaner
2) Uninstall applications that haven't been used in recent months.
3) Clear up your desktop and move the files to C:/ or to your user file. Files on the desktop use swap space on your drive to be quickly available, but hog system resources especially if you've got 60GB of photos sitting pretty on the desktop.
4) Defragging the drive if the user is running XP, 2000, or NT4.0
5) Emptying the recycle bin and limiting the amount of space the recycle bin and system restore takes up.
6) Use msconfig to disable services and start-up applications that don't require their services to be run.
7) Disable automatic updates on programs that don't need to be regularly updated.
I find that things like Windows updates are less efficient at updating the system than a full service pack. I also am of the opinion that most drivers (especially printer drivers from HP) don't have to be updated, with the exception of graphics drivers. Its easier to wait three or so weeks after a driver release from Nvidia or AMD so that bugs are ironed out and things are sorted.
Jmak stole my thunder again with a good summary of your points. Most of them are good advice, and could form the basis of a more in depth set of articles later on.
A brief overview:
1) Good advice
2) good advice, though some reminents will remain in the system, especially when you deal with applications such as itunes.
3) What Jmak said. A clean desktop would probably result in a faster boot time, though I'd be keen to learn more about this if you have the time and links to your info.

4) Defragging the drive on any OS is a good idea(yes even vista and 7), though I've found the performance gains are minimal, especially when dealing with the main OS drive. This also depends on whether you keep your core OS + applications on your OS drive, or if you use it for storage too. If it's used for storage I'd probably advocate a Defrag more.
5) I wouldn't advise limiting system restore, but different strokes for folks. As for emptying the recycle bin, I'm not entirely certain that this would speed up a system in any noticeable way. Would be nice to test though.
6) If you're familiar with msconfig or regedit then you're not part of the articles target audience.

Note I mentioned "well known" techniques in the article, contrary to popular belief msconfig is far from well known(and can in some cases be dangerous).
7) I disagree, I don't find automatic updates degrades performance enough to be noticeable. Like I said in the article, updates often bring with them increased performance through optimisation, as well as great security.
Also, for those users who don't have a paid-for anti-virus, an anti-virus with a smaller file footprint may also be the answer. AVG uses about 45MB on average for me on Windows 7 32-bit, and about half that on 64-bit. Avast is also quite frugal with system resources.
Indeed, that's what I tried to bring forward in the article, that a free, less resource intensive version of an antivirus along with windows updates offers a good level of protection and a small bump in performance. AVG and Avast are fairly good, while in my experience BitDefender and Norton(paid versions) tend to hog resources.