Okay, I know you guys are all gonna hate me!
But hey this is a site where you are free to give your opinions without fear, or isnt it? Anyways here are some examples IMO why you shouldnt use Linux (this is especially created for the Windows Users):
1. Its extremely complicated! For a Windows user, Linux is very complicated and takes a lot of time to get used to, if you even get!

Here is an example of how installation of a program works on Linux:
export CFLAGS="-mcpu=athlon-xp -pipe -O4"
export CXXFLAGS=$CFLAGS
./configure --prefix="/usr"
make
make test
make install
What the Hell! You just need to be extremely high tech guy or a simple nerd to undrestand this!
2. Almost no Support.
Although in the past it didnt work with anything now it is recieving much more support altough not enough. Some programs you used in Windows will not work and if you want some of them to work youll need to download a program that lest you use Windows Programs (not sure how this works) Good luck trying to install the program Windows User!
3. Gaming
for the Gamer Linux is the last OS besides MAc that passes on his mind when he want a OS to play Games. It has almost none in support regardeless games, (although games like UT 2003, and other have versions to Linux, but just a few) And I know there are programs that you can use to make the games work but isnt it easier to just stay with Windows?
4. Problem solving
Who are you going to ask when suddenly the OS wont boot and it give you some strange errors? Send an email to the Linux crew? Call the help line? Call 911?
More than 90% of the earths population uses Windows, so you will at least find a person that can help you if you have a problem in Windows and many problems are more known in Windows than Linux just because of this...
5. Bugs
You will say, Windows is FULL of bugs, Linux has almost none! Well true but this is in reagards to the KNOWN bugs, what about the unknown bugs? Im sure many bugs are found in Windows because the majority uses it, period.
6. Pirate Heaven
Linux is extremely easy to make copies and "pirate" it, most critizise MS for the activation but im sure the pirate will have a living hell trying to pirate a XP version... Its easy to copy Linux because its freeware. Freeware has it advantages and disadvantages, remember that. For a free downloadable version of Linux you do not recieve support at all, want support buy it!
7.Ugly
Although the eye-candy is fair/ sometimes very good, the windows and the startmenu seems IMO very cheap. Just look at the clock for god sake! How ugly is that! If you want beauty get Mac!

And the Linux users seems to take the eye-candy as a good thing but I am sure they have critized XP for its "fisher-price" look, childish look, mac look, etc, havent you?? Got ya huh?
8. Internet
Although it finds your connection to the internet and you can imediatelly surf after you have installed it if isnt that easy and nice for a Windows User. for example every time you go to a page where it is required cookies it asks you for the damn cookie if you accept it, in the beggining youll see it as a + thing and secure but with time its just so damn annoying!
9. Bloated
How many here critizied XP for being Bloated? Just look at Linux, more than 75 games included! Come On! Its full of programs that maybe you wont even use! So many things! Its too much. Bloated as hell!
10. Just for High Tech People
Linux is by far not recommended for the normal user or Windows user just because its so different and dificult to manage. Maybe as a server OS it is okay but for the typical user, no no, stay away from it! Will take you eternity to get used to it and days to at least know where to go...
IMO Linux can maybe in the future become a strong enemy to Windows but for now its just too different and it needs more work on it as well as support and compability.
I myself have use SuSE, Mandrake, RedHat, Connectiva, etc , oh and there are just so many that you dont even know from the beggining which one to choose! Why so many and they release frequently new ones very time (and many critisize MS for making an OS every 2-3 years! lol

)
Many, and believe me, many will hate me now with this post but its my opinion, I have the right to voice it!
Most Linux ppl try to put on your head that Linux is the best and so on... Keep trying fellows...

Good Luck!
durante