Good things about Linux:

Morality. MS is a company full of shysters, and $300 is too much to spend for their inferior operating system In a few years when Longhorn comes out, and DRM (Digital Rights Management) sorts of crap starts taking effect, you may one day be unable to run any software or play any music or watch any movies that aren't "digitally signed", i.e. that you don't have a copyright to use. Every OS MS produces takes away just a little bit of your right to do what YOU want to do with the computer YOU paid for. How ridiculous is it that you have to contact their website, transmit some kind of hash value based on your hardware, and get permission from MS to use the software you already bought? MS has been convicted in the US of abusing their powers as a monopoly; that means they are LEGALLY GUILTY of ripping their customers off. They're close to being taken to court for the same exact thing in Europe at this time. Why would you want to give them more of your money to RENT a license, and basically beg them to allow you to use their crappy OS?

Technical superiority. Linux doesn't deteriorate just from daily use, like Windows does. Linux doesn't have such a thing as a Blue Screen of Death; if something crashes, you know why, and you can fix it. Linux doesn't do mysterious magical background things without telling you about it. Linux doesn't grant every program on your system administrative priviledges. Linux doesn't come installed with 27 "services" listening on various ports by default, waiting for viruses to arrive. Linux has technical problems too, yeah, but 99% of Linux problems are BKAC problems. "Between Keyboard and Chair."

Choice. Linux gives you options. Windows forces MSN and MS Office and MS Whatever down your throat. There are dozens of window managers for Linux, from bare-bones no-graphics-at-all to fully integrated "Desktop Environments". And I can use any of them, simultaneously even, or I can use none at all if I wish. I know exactly what is installed on my computer, because I put it there, not MS. There are hundreds of choices of distro alone. From ultra-newbie to ultra-advance. There are Linux clones designed to look exactly like Windows. There are Linux clones to do nothing but run a server or router. And there's everything in between the two.

Freedom. Linux is free as in money, because you don't have to pay for it. It's the product of programmers who program for the sheer joy of programming. I don't put up with nag-ware, spy-ware, ad-ware, etc. in Linux. Linux offers many free office suites, free graphics programs, free music programs, free everything. Windows: $300 for the OS, $400 for Office, $20 for the ability to skin the OS, $100 for anti-virus programs, etc. etc. etc. Linux is also free as in speech. The entire community shares their source code and their work with each other. Linux is almost scientific in the way it progresses. MS on the other hand hoardes its source code to keep any competition from having access to their "secrets", and uses that advantage to rape your wallet.

Power. Linux is more powerful for many things. It takes programming knowledge to get at a lot of the "power", but it's there if you want it. Everything you can do in Windows, short of a few very specialized applications, I can also do in Linux, and I can also do way way more.

Fun. Linux is fun to use, plain and simple. That's a matter of opinion though.

Bad things about Linux:

It's hard to learn. Yes, it is. Especially since you have to un-learn a lot of the total garbage that's built into Windows. The learning curve is steep. It takes a huge leap of knowledge to get a foothold. Things that take 2 seconds in Windows often take 2 hours in Linux, especially at first. However, once you have Linux working, it WORKS. There is no "double-click and icon and pray" in Linux. But I for one don't miss it, because half the time, Windows does the wrong thing, in spite of your prayers. I, on the other hand, do the right thing.

Hardware support. MS has half the world in its back pocket, so many companies (hardware and software) don't support Linux. However some notable ones do. NVIDIA does. There is good Creative support. Few games support Linux, but some do, like NWN.

Basically, if I wanted user-friendliness, I'd get Mac OSX. If I want a good computer to use for anything I want to use it for, I'd use Linux.