Many of those friends just went out and bought a new computer that is faster and came with a new version of Windows (which they thought would be better). However they never took into consideration that with every version of Windows comes a whole new learning curve... How to use it? Plus the newer versions used more of the computers resources so the speed it operates is not really that much faster than the old one.
Windows operating systems, like versions of Office, are completely different in how they work, or more precisely, where are the resources hidden that I used to use? In essence Windows versions are like Linux Distributions. When you find the 'distro' you like you stick with it. There are hundreds of Linux 'distros' out there to choose from. The below video will show you a couple that are the main or recommended ones to try.
So if you just bought a new PC with Windows 7 or 8 and you are left with an old computer that you are just going to throw in the bin... WAIT! Try Linux first on that old PC. You don't need to worry about loosing your files as we aren't going to be using the hard drive on the old PC. The PC does not even need a hard drive installed at all.
Now watch how much faster your computing experience has become. Browse the net faster, use your internet banking more securely. Edit video or photo's so much faster. The whole computing experience is just what you thought you would get with a new computer. Only thing is... it's on your old one.
Watch the video and see for yourself.
Now compare the speed of your new PC with Linux installed on your old one. Was it worth the money? Not convinced? Wait 6 months and compare speeds again.