[Off-topic] N8ter:
Google. I'm not going to waste time responding to this uber-rhetorical question. POP/IMAP doesn't even compare to Exchange, and Exchange allows you to access mailboxes via POP or IMAP anyways - not that I can see why anyone would do that, when you get Outlook with each Exchange CAL.

That's like using Thunderbird to access Hotmail via POP when you can use Windows Live Mail and get it pushed to you via DeltaSync.

Complain to IBM that they don't use standards in their Lotus products. If they were going to use just POP/IMAP, companies like Microsoft/IBM wouldn't need things like Notes/Exchange. They would have just spend less money building and supporting simple POP/IMAP Mail Servers.

Linux sound is Fragmented as hell. You obviously aren't a software developer... This has been a well-known issue with Linux since the dawn of time. The fragmentation among Desktop Environments is another problem. It can create training issues when one person uses GNOME and another KDE/XFE/etc. and if you force people to use a Desktop Environment they are not familiar with, their productivity drops substantially for an undetermined span of time while they relearn how to use their computer efficiently/productively.

Graphics cards are deprecated twice as fast on Linux than on Windows because it is a PITA to keep the proprietary drivers updated for the latest kernel versions. Linux does not have any stable kernel ABIs, so any kernel patch can potentially break the proprietary drivers. This isn't just graphics card drivers - it can break any kernel driver. There is also the issue with supporting later X.Org versions, as well as changes in Base/System Libraries. Linux distros seem to love to API hop as well. You never know what the next version will swap out (SELinux? AppArmor? OSS? ALSA? KDE? GNOME? What version of GTK/Qt? etc.).

Linux is not an OS that puts much thought to Backward/Forward compatibility (unlike e.g. Solaris). That is also part of the reason why there is no proprietary consumer software market to speak of. Why do you think Linux has no decent games on it? Cause the developers are lazy?

Well, actually... Considering the amount of work that would require... I guess laziness can be an acceptable excuse.

Server applications aren't affected as much because those systems do not run Auto-Updaters and they are managed by System Admins that (should) research, cherry pick, an test patches before they are deployed to production machines. Those machines are usually behind corporate firewalls running corporate A/V software, etc. (yes, even Linux Servers run A/V - spreading malware is as bad as being infected yourself, and can be considered negligence).

Eww.

Macs are overpriced, but unless you have a complete crap machine (hard to imaging with the way Apple controls the hardware... maybe I should say a very old machine with a recent version of OSX on it?) it isn't unreliable or sluggish.

The problem with Macs are that they use the same hardware (sometimes worse) inside than pretty much every PC Manufacturers, with a cute UNIX OS, a crappy mouse and keyboard, and a nice case... Then they add $400-1000 onto the price and try to sell it to you. The quality of the machines are generally about as good as any good PC desktop (i.e. I wouldn't call a cheap eMachines a good PC desktop) or notebook. Macs are generally less customizeable, as well. A PC or Notebook customized to an Apple Price is factorably better than the Mac, 98% of the time.

OEMs license Windows for close to nothing. Linux's price is no advantage, and the issues with supporting is much more than for Windows.

Dell tried putting Ubuntu on Netbooks and they were getting returned left and right. Most of the other people took Ubuntu off and put XP on them.

Linux isn't free. Nothing is. Just because you aren't bearing the costs, does not mean it is free. A really good Linux Distro (like RHEL) is not free, though. It costs as much as Windows 7 Home Premium - more depending on what "options" you choose (and people cry about Microsoft's SKUs).

Ciao.