Why does Microsoft Windows get slower day after day?
Even the latest version of Windows has a number of serious design flaws resulting in it becoming slower and slower as time goes on. You've probably heard more than once someone say "My computer is getting sluggish, I'm going to reinstall". Reinstalling Windows solves the problem... until the next time.
You may think this is just how all computers work: That they have very new technology, and they just are not really stable yet. Well, try Linux and you'll be surprised. Five years from now, your system will be just as fast and responsive as the day you installed it, not to mention that you won't have any viruses, adware, trojans, worms, etc., that would force you to reinstall anyway.
I have managed to convince many people to switch to Linux, while keeping Windows on their hard disk, because they needed to use some piece of software that Linux doesn't have (like Autocad), so they use both systems. Since the day they switched, most of them have reinstalled Windows about once in a year or two; but Linux didn't let them down, and is still running perfectly well and is still snappy today.
Linux lets you spend more time surfing, working, and playing and less time reinstalling over and over again.
Reporting bugs
If you find a bug in Windows, you can basically wait and pray that Microsoft will fix it and fix it fast (and if it compromises your system's security, you would have to pray twice as hard). You might think that reporting that bug to Microsoft (so that they can fix it more quickly) must be easy. Well, think again. What if Microsoft doesn't even notice the bug? Well then, let's hope the next version of Windows will fix it (but you'll need to pay another few hundred bucks for the newer versions of both the operating system and the software that you were using).
Nearly all open source software (including Linux distributions) have a bug tracking system. You can not only file bug reports (and you're encouraged to do so!) explaining what the problem is, but you can see what happens next : everything is open and clear for everyone. Developers will answer, they also might ask a little extra information to help them fix the bug. You will know when the bug has been fixed, and you will know how to get the new version (still for free, needless to say). So here you have people taking care of your problems, keeping you informed about it, and all that for free! If the problem is solved on your system, it will be on everyone else's : it is in everyone's interest to work together to make software better. This is how open source works.