If your PC is already in a sad state similar to the one we experienced, you may want to consider a full system restore. You may also be able to get your system back to some semblance of sanity with our list of tips to keep your computer from slowing down.
But if your computer is still purring along like new, how do you keep it from winding up like our test system? By using some basic Web savvy, common sense, and having the patience to read a bit before you click.
Avoid clicking on sponsored links
Pay attention to your search results and try not to click links bordered by that yellowish rectangle, or otherwise connoted as ads. Someone's paying for their prime placement. And for the most part, they aren't doing so for your benefit. (Note that this applies only to downloading software, not necessarily to sponsored links for a lot of other things.)
If this seems obvious to you, maybe your friends and family members could use the advice. If you see them installing something this way, let them know the smarter way to surf.
Get your software from the source whenever possible
To install Flash or Acrobat, head to Adobe.com and search for it there, or use your favorite search engine and pay attention to the source of your links. In other words, read the URL before clicking, and try to get your programs directly from the developer. Download iTunes only from Apple. Java should come from java.com or Java's owner, Oracle.
It may not always be obvious who the developer of a given program is, so read the URL you're about to click on. If it isn't familiar, check out the site name itself using a search engine. Doing so will quickly let you know, for example, that videolan.com is the developer of the VLC video player. Trust us, it's worth taking an extra few seconds versus the hours you may spend later dealing with unwanted software–or worse.
Familiarize yourself with a few trusted file download sites
You can't always get programs directly from their developers. But you can find many popular programs at Cnet's Download.com, SourceForge.net, Tucows, or FileHippo.com. All of these sites have been around for many years and have some of the biggest repositories of free or trial software.
If you can't the program you're after on one of these sites or on the page of its developer, you should seriously question what you're downloading. If a search turns up what you're looking for on an unfamiliar site, check out that site with a search using Google, Bing, or Yahoo.
You still may wind up with unwanted software
Even if you get your program directly from the developer or one of the above sites, there's a good chance that a toolbar or some other unwanted program will attempt to tag along. Just about every free software site these days pushes something extra with the install file, such as adding toolbars and/or attempting to change your default browser or search. This is frustrating, but still less nefarious than what we experienced from unfamiliar sponsored sites.
If you pay attention when you're installing, you can usually avoid getting anything extra. Skim any user agreements you see on the screen. Responsible sites make it clearer before they try to add things you didn't ask for. You can usually click the “decline” button and still get the app you're after, or uncheck a box to skip the toolbar or, say, the hijacking of your search provider.
Also, resist clicking the Express Install option, which often defaults to giving you whatever the given site is pushing. Clicking Custom Install often reveals hidden options that let you ditch the junk before it makes it onto your PC.
Learn to love your uninstall screen
Finally, accept that you probably won't catch every unwanted toolbar before it gets installed on your system. It happens to all of us—these days more often than ever, it seems. That's why you should peruse your installed programs list (the Programs and Features control panel in Windows) regularly, at least every couple months.
Scroll through the list and look for applications you don't recognize or remember actively downloading or installing. If you're unsure of what a program is, you probably don't need it. But if you're unsure, check it out via a Web search or try launching it. If that doesn't jog your memory, you can probably safely kick it off your hard drive. Unless it's a program you had paid for, if you change your mind later, you can probably download it again for free.