Most every Linux distribution has a package manager, and that's one of the first things you need to find. In Ubuntu, it's the Ubuntu Software Center, and it is your friend. With the package manager, you'll be able to find just about any software you need, and probably for free.
4. Fearing the Command Line
It's a testament to how far Linux--and operating systems in general--have come that many people have never had to use a command line. With distributions like Ubuntu Maverick Meerkat, you still won't have to, for most purposes.
Don't live in fear of the command line, though. It's no more difficult to type in a few short commands than it is to click through the necessary screens in a GUI, and it can be both faster and more effective. I'm not saying you need to seek it out, necessarily, but if something comes up that requires it, don't stress out.
5. Giving Up Too Easily
Change can be hard, no matter how simple the technology you're changing to might actually be. It's important to remember that you weren't born knowing how to run Windows or OS X, either--you had to learn and get used to it.
Same goes with Linux. It might feel a little different from what you're used to, but that doesn't mean it's hard or bad--it's just different. Stick with it just a little longer, though, and you'll soon stop noticing the areas where it's different from Windows or Mac. Stay a little longer, and you'll start seeing that many of the ways Linux does things actually make more sense. After that, it won't be long before you can't imagine going back.
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