I have been around the forums since last year, and have experienced this myself. It seems each new user to Ubuntu wants to preach its benefits to everyone and convert the world. Let me ask you this: when was the last time this worked to convert you to anything? It just doesn't work with humans. If you try to force the decision on most people, they will reject it. Its great that you love it, but maybe it won't work for someone else, or they are happy with what they have. Ubuntu isn't the end all operating system, it does have its flaws.
Instead of trying to convert everyone by preaching to them, just mention it when asked. Carry a livecd or usb so that when you are using someone else's computer you can use that on it to do your stuff. They will naturally be curious when you boot up to it. Just use it, and if they ask you questions patiently and kindly answer them. If this were to happen, not only would we get more people trying Linux, but we would have less rants in the User Testimonials & Experiences section, since misinformation would be less likely to be used to try to make them change.
Have a nice day/night everyone! Remember this the next time you go to preach!