Having Linux on your PC, either primary or secondary has many benefits. Some of the obvious ones are:
Forget about viruses:
If your computer shuts itself down without asking you, if strange windows with text you don't understand and all kinds of advertisements appear when you don't ask for them, if emails get sent to all your contacts without your knowing it, then your computer probably has a virus. The main reason for this is because it runs Windows.
Linux hardly has any viruses. And that's not like "Oh well, not very often, you know". That's like "If you've ever heard of a real Linux virus, please tell me". Of course, a Linux virus is not impossible to get. However, Linux makes it very hard for this to happen, for several reasons:
Linux uses smart authorization management. In Windows you (and any program you install) usually have the right to do pretty much anything to the system. If you feel like punishing your PC because it just let your precious work disappear, you can go inside the system folder and delete whatever you want: Windows won't complain. Of course, the next time you reboot, trouble begins. But imagine that if you can delete this system stuff, other programs can, too, or just mess it up. Linux doesn't allow that. Every time you request to do something that has to do with the system, an administrator password is required (and if you're not an administrator on this system, you simply can't do it). Viruses can't just go around and delete or modify what they want in the system; they don't have the authorization for that.
Don't pay $300 for your operating system:
(And don't copy them illegally)
You're probably saying to yourself : "Oh, I didn't pay for Windows". Are you absolutely sure ? If your computer came with a copy of Windows, then you paid for it, even if the store didn't tell you about that. The price for a Windows license amounts to an average of one fourth of each new computer's price. So unless you obtained Windows illegally, you probably paid for it. Where do you think Microsoft gets its money from?
On the other hand, you can get Linux completely free of charge. That's right, all these guys all around the world worked very hard to make a neat, secure, efficient, good-looking system, and they are giving their work away for everybody to use freely (if you wonder why these guys do such things, drop me an email and I'll try to explain the best I can :) ). Of course, some companies are making good business by selling support, documentation, hotline, etc., for their own version of Linux, and this is certainly a good thing. But most of the time, you won't need to pay a cent.
Linux and "Open Source" software are "free". This means their license is a "free license", and the most common is the GPL (General Public License). This license states that anyone is allowed to copy the software, see the source code (the "recipe"), modify it, and redistribute it as long as it remains licensed with the GPL.
So what do you care about freedom? Imagine that Microsoft disappears tomorrow (okay, that's not very likely, but what about in 5 years, 10 years?). Or imagine it suddenly triples the price for a Windows or Office license. If you're tied to Windows, there's nothing you can do. You (or your business) relies on this one company, on its software, and you can't possibly make things work without it (what good is a computer without an operating system?). Isn't that a serious problem? You're depending on one single company and trusting it wholeheartedly to let something so important nowadays as your computers work the way they should. If Microsoft decides to charge $1000 for the next version of Windows, there's nothing you can do about it (except switch to Linux, of course). If Windows has a bug that bothers you very much and Microsoft won't fix it, there's nothing you can do (and submitting bugs to Microsoft isn't that easy, see the "Report bugs" section).
With Open Source, if a particular project or support company dies, all the code remains open to the community and people can keep improving it. If this project is especially useful to you, you can even do this yourself. If a particular bug annoys you, you can submit it, talk with the developers, but even better, you can fix it yourself (or hire someone to do so), and send the changes back to the upstream developers so that everyone gets the improvement as well. You're free to do (nearly) whatever you want with the software.
Update all your software with a single click:
Windows has a pretty convenient tool called "Windows update", which allows you to update your system with the latest updates available.
But what about all your non-Microsoft software ? Adobe applications ? ZIP compressor ? Burning program ? Non-Microsoft web browsers and email clients, etc. ? You need to update all of them, one by one. And that takes time, since each one of them has its own (auto-)updating system.
Linux has a central place called the "Package manager", which takes care of everything installed on your system, but also every single piece of software your computer has. So if you want to keep everything up-to-date, the only thing you need to do is press the "Install Updates" button down there :
Are your tired of restarting your computer all the time?
Have you just upgraded one or two little things on your Windows system with "Windows update"? Please reboot. Have you just installed some new software? Please reboot. Does your system seem unstable? Try to reboot, everything will probably work better after that.
Windows always asks you to restart your computer, and that can be annoying (maybe you happen to have a long download going on, and you don't want to interrupt it just because you updated a few pieces of your system). But even if you click "Restart later", Windows still keeps bothering you every ten minutes to let you know that you really should restart the computer. And if you happen to be away from your computer and you didn't see the question, it will happily reboot automatically. Bye bye long download.
Linux basically doesn't need to restart. Whether you install new software (even very big programs) or perform routine upgrades for your system, you will not be asked to restart the computer. It is only necessary when a part from the heart of the system has been updated, and that only happens once every several weeks.
Do you know Internet servers? They're the big computers that answer you when you ask for a web page, and send the information to your browser. Most of them run Linux, and since they need to always be available (a visitor could come anytime), they aren't restarted very often (services aren't available while the system is starting). Actually, many of them haven't restarted for several years. Linux is stable, it runs perfectly well without restarting all the time.
You'll probably not let your computer stay on for several weeks but the point is: the system won't bother you with restarting all the time.
For more reasons to get Linux go to http://www.whylinuxisbetter.net/
You might not want to stop using Windows, but do give a try to Linux, you might like it so much that you will start using Linux for normal everyday usage. I tried Linux earlier this and now use XP only for playing games (FIFA08).
In my next post I will explain 'What are distros?' and how to chose the best one for you.