Some software has an unfortunate tendency to assume that it's the most important thing ever to be executed on your computer. Programs of this type will add links to themselves in multiple menus and on your desktop, set themselves up as the handler for any file type vaguely related to their function and have themselves set to run at startup. This may be done for malicious reasons, but for software that's at least technically non-malicious it's done because the developers overestimate the utility of their software or just don't care that you're incurring an unnecessary overhead due to their software. This kind of behaviour seriously irritates me. Running all this crud consumes system resources that would be better expended on the tasks the user actually wants to perform and seriously slows down the time for the computer to start up. It also exposes the user to security and stability issues in each of these components. This is compounded by non-technical users often not knowing this software is running at all, which means they are unlikely to ever update or disable it.

Tools like autoruns can be useful in disabling the autoload features of software. This is useful when you need the software (such as document viewers and movie players) but your need doesn't warrant wasting system resources on it constantly. There are a number of big vendors who should really know better who vastly overestimate the utility of their software and load most of it at startup. Killing this behaviour means a slightly longer wait when you actually need their software but the resource saving for the general case of not needing it will result in a better overall experience.

If you start your system and your notification area has more than about 5 to 10 items odds are you're loading a lot of crap that serves the interests of some bastard marketer but does nothing for you. Go in and kill it all to reclaim the wasted resources on your computer for purposes that you want, not what some random vendor wants you to have. It's your system, demand control.