msconfig is a great utility, but if you don't know what you're doing, it could be disastrous, like ending processes in the task manager. One way I found to stop these long winded startups is by making sure that when you install an application, you unclick the create quick launch icon. Many applications give you that option. If you boot up your PC it loads these applications to your quick launch, and it literally loads the app as it would if you double clicked on it, so its constantly running in the background, even if you don't need it. With a lot of these apps you can right click on the icon in quick launch and exit it, but most times it comes back to the QL when you restart your PC, so its better to eliminate it completely by making sure the quick launch icon is not created in the first place.
CCleaner is brilliant, and it will only show files that can be deleted safely without harming Windows. Another way, when it comes to clearing cookies and web cache etc. is to set browsers to clear everything automatically when you close off the browser page. I have set my firefox up like that, but when someone uses Chrome, I need to manually go to the temporary internet files to clear them (so I would need to set that up as well).
I agree there. Having tons of programs installed when you aren't using them is carrying deadweight around on your PC as it takes up resources (space) you could use elsewhere. Most times an uninstall is enough, but sometimes they leave a few files behind in program files. It is generally safe to delete these files manually, but if windows gives you a message saying that the resource you are trying to delete is shared, its best to leave it be for now and not delete it. Sometimes applications (like my HP PSC software) installs more than one application, so its best to look out for that in the add/remove programs in the control panel. Here you can use external harddrives to keep documents and other downloaded applications etc. so that your main drive that holds windows remains clutter free. I also use Sata drives as backup storage.
Defrag. I'm not a huge fan of it to be honest, and call me crazy, I don't generally use it. All it does is take files that are all helter skelter all over the place and put it back where it belongs, and to be honest, with an 80 Gig hard drive (at least) you are looking at a good few hours before you could actually use the PC again, and when its done, the difference it makes is so small you hardly notice it. The bigger the hard drive, the longer it takes to sort through everything. But that's my 2

and is up for debate
Antivirus.. for me that will always be a bit of a toss up. You have antiviruses that only scan files when you open them, you have some that scan constantly, and the latter can slow down a PC when they do this. I use Avast on my desktop and I have tend micro on my laptop, of which trend micro is intensive, while avast is not. Ones I know that are intensive are Norton (hates games as well most times), Panda, McAffey, and Kapersky.
Another grey area for me. Less is more, yes, there I agree, but the use of software to control these processes is not something I can easily agree to. If you follow any of the other 6 points in the blog post, then you won't really need software. The only software I have on my PC are for diagnostics and most of them are already part of Windows. Updates are important yes, but most times where bandwidth might be a problem, selective updates might be a better idea. You can set your PC to ask you what you would like to update and it won't download anything until you tell it. Updates that
need to be done are security updates for windows, malicious software removal updates and other important Windows updates like that. For software, I would say that the programs you use daily or your most important software like your antivirus takes preference. Drivers will always be important, so most times you will get updates for your motherboard and BIOS, other components you connect to your PC, and your graphics card. Those, to me, are the most important.
If you find that your PC is already on that less is more basis and only have things installed that you need/use frequently, but it is still slow, one other thing you could do is enlarge your page file and virtual memory. Windows has a recommended setting for these and generally is set lower than the recommended value. You need to be careful there though, because when you increase that number its taken from a harddrive specified when you increase it (Usually its C:/) You need to make sure that you leave space on your harddrive for it to use the space as virtual RAM. Other than that, you can plan what you are going to do with the PC before you buy one, or upgrade, and then make sure the one you get/build is a little faster than what you are going to need.

I'm babbling....