Feanor

None.
I've been trying the main 3 free antivirus, AVG, AVAST and ANTIVIR. Now, AVG version 8 doesn't even install correctly on Win2K (scheduler and updater are disabled), ANTIVIR sucks a lot of resources, takes forever to open dialogs and gives me a BSOD from time to time (probably only when it finds some other software running, do not know which), AVAST is the most complicated antivirus ever, with several resident modules for monitoring different activities, a skinnable GUI, options distributed in "hard to find" dialogs here and here. On top AVAST misses heuristics besides the mail module.
At the end, given the catastrofic failures of AVG and ANTIVIR I am using AVAST, with the bare minimum of modules installed but thinking of living without any "on access" scanner and use CLAMAV (ported to Win) from time to time.

Edit: did I say AVAST? So far I got this interesting "features":
1. scanning my 170MB Thunderbird mailbox it generates 2 or 3 120MB temp files, if I stop the scanning before it ends those temp files are left on the disk in the _avast_ directory. It seems also that after creating those files AVAST doesn't actually do anything, skipping the content. On a side note, ClamAV does the same with temporary files if you "cancel" before completion.
2. there is a feature to block (it asks for authorisation) writing of executable files, unfortunately it is triggered also by directories whose name is "mario.com" and some software installers create such folders, for example TopStyle. An alert is risen any time you access a dir if some subdir has such names.
3. automatic updates of the virus signatures can cripple the scanning engine.

I played with Ubuntu, Kubuntu and Xubuntu lately.
For those who don't know about it, they are different flavors of Linux, the free and open source operating system, on top of which you run several layers of free and open source different software.
Linux is named after its inventor, Linus Torvalds and it is composed by a "core", called Kernel plus a software, the X Window System, that manages the graphics on top of which you can chose different desktop environments.

There are many many different flavors of Linux, called "distros" or distributions. In short they are packages that allow you to install kernel+X window system+desktop environment+applications so at the end you can have a more or less complete computer system that works like Windows or Mac.
Years ago installing, setting and working with Linux was difficult because you needed a lot of work and computing knowledge. Today the "distros" have evolved so things got much easier and you don't need to be an expert.

So why everybody is not using Linux? Mostly because there are still difficulties to make all the hardware devices work and because the software you get on Linux, besides networking and maybe software developing, is fewer and not as good as it is on Windows or Mac. Using Linux you get the freedom of doing pretty much what ever you want but the price of it is Linux being a collection of things from sparse sources that contribute to Linux with their own reasons, goals, schedule and rules.

My experience with Linux is a mix of pros and cons. So far the main feeling is you can make Linux work like the other systems but it takes a much bigger effort. I guess the average guy considers the money you have to spend to buy Windows or Mac plus the software that runs on top of those against the time you have to spend trying to learn how to make Linux work, plus the inevitable frustration when things go wrong and the possibility that some issues can't be fixed anyway. And of course some things do look and work better on Windows and Mac than Linux, for example the software for multimedia tasks. Right now I am trying to learn how to use Gimp and the feeling is something like "OMG the most difficult and illogical software ever" . Hints, help, suggestions, comments are welcome.

Among the three distros I named above, Ubuntu is the one that works better "out of the box", while the other two, even if they share a common "base", need more work to get all the things ready. Besides that, it is mainly a matter of tastes about the desktop environment.

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I am too lazy, italian readers please go on my "real" blog here: http://eldalie.blogspot.com, thanks.

Here is a nice little PDF reader you can use instead of the Adobe Acrobat Reader.
What is Sumatra PDF?
Sumatra PDF is a slim, free, open-source PDF viewer for Windows.
Why another PDF reader?
Sumatra has a minimalistic design. Simplicity has a higher priority than a lot of features.
It's small and starts up very fast.
It's designed for portable use: it's just one file with no external dependencies so you can easily run it from external USB drive.

Ecco un piccolo lettore per il formato PDF che potete usare invece di Adobe Acrobat Reader.
Cos'è Sumatra PDF?
Sumatra PDF è un piccolo lettore PDF per Windows, grautito e open-source.
Perchè un altro lettore PDF?
Sumatra ha un design minimalistico. La semplicità ha la prioritè più alta rispetto alle molte feature.
E' piccolo e si avvia molto velocemente.
E' disegnato per essere portabile, si tratta di un solo file senza dipendenze esterne cosi potete facilmente farlo girare da un drive USB esterno.

Web site: Sumatra PDF - a PDF Viewer for Windows