Ok, but is there any real advantage? Also, what about security?
For most people with Win7 and Avast (for example) there is not much of a difference. Win7 will work out of the box for majority of people, and it will be good enough for a long time.
If you do some risky activities (like searching for illegal MP3 or DVD downloads, or pirated software, on Chinese Web sites) then Windows is not even an option for such a thing. Nothing is, really, except a disposable VM image (VirtualBox) that you discard after each browsing session.
All in all, Linux will work just as well, if not better, but some normal activities will be hampered. I don't know, for example, if iTunes is supported. There were some issues with BlueRay disks too. Generally if you have a good deal of Windows software (especially if it is expensive, like AutoCAD) then there is no reason for you to switch to Linux. But if you are building a laptop for the kitchen then Linux sounds like a good solution; upgrade from XP to Win7 would cost more than the laptop itself.
Security-wise, modern Windows is not that bad, but Linux is still better. If you need a top-notch security, though, you need OpenBSD (and it is only for UNIX gurus.)
Linux security is generally better than Windows for most users. The bad stuff is Windows-specific and just won’t run on Linux.
This isn’t to say that there aren’t security issues, just that the bugs and exploits target the huge Windows user base since there isn’t an economic incentive to go after Linux users. That said, the security model in Linux is pretty equivalent to that on Mac OSX.
If you’re using a computer to play media, browse the web and do basic tasks like word processing and email, Linux does a good job. Finding and installing applications in Ubuntu is easy with a program that works much like an app store. You just find the program you want and install from one central repository. No downloading and installing like Windows.
The downside is that most Linux software apart from server applications is a bit behind the best Windows and Mac software. Programs like Open Office or the photo editing program Gimp are always trying to catch up with MS Office or Adobe Photoshop. They do basic things well, but as an example, if you need color management for pre-press, you can’t use Gimp to edit photos.