Windows only has "user-installable drivers" if you don't pay attention to the fact that you're effectively sudo-ing when installing them. Driver installation is an Administrator level task, as it should be. On a Linux system, when you're in Gnome and use a GUI package manager to install a driver or any other package, you will be asked for a password to either su to root (on Fedora/RHEL/CentOS) or sudo (Ubuntu). This is the same as being asked to confirm on Windows when running as a user with administrative privileges.

And, I'm not sure I buy that Linux is a backwards wasteland on this front. It has more drivers than current Windows versions, and more of my hardware, particularly stuff that's more than two or three years old, Just Works in Linux. I usually have to go digging on the web to find drivers for at least a few devices on any particularly laptop or desktop machine when I install Windows. That's usually only the case for more advanced 3D drivers on Linux.

Windows does have a more stable ABI (the last change, I think was from XP to Vista), while Linux does not. This could be argued to be a point in Windows favor. When the ABI changes, a driver on Linux has to be recompiled. This was historically defended by Linus based on the fact that the majority of Windows crashes are caused by 3rd party drivers...and Linus wanted Linux to be as immune to those poorly made 3rd party drivers as possible by making it hard for them to exist. Drivers in Linux, generally speaking, would go across Linus' screen (or at least one of his lieutenants) at some point, making it possible to insure a high level of quality and consistency in anything that ended up in a position of being able to bring a Linux system down. Linux historically has extremely admirable reliability because of this (and other factors).

The trade-off is that 3rd parties, like hardware companies, cannot release a driver and forget about it. A driver for Linux released in binary-only form today will not be useful in a year or sometimes even a few months. But, that's also proven to be true for Windows now that Microsoft has changed the driver ABI and raised the barriers to building drivers for Windows. A Windows XP driver is useless on Windows 7, so vast swaths of previously Windows-compatible hardware is no longer usable with Windows.

Linux also has apt-get (or yum) for drivers. When you update your kernel, you update all of your drivers to the latest version. Since drivers are tiny and disks are big, there's little reason to have them all packaged up separately. And, Debian/Ubuntu and RHEL have methods of distributing drivers separately from the kernel in package form. It's just rarely used, since so many drivers are included in the kernel.

So, I have historically found Windows to have better driver support, and it is occasionally more convenient to get hardware running under Windows than Linux. But, the gap has shrunk remarkably in recent years (nVidia and ATI both provide pretty good drivers for Linux now, and Intel has for a very long time), and lately I'm more often frustrated by Windows than Linux, since I have some older hardware that was quite expensive that I'd rather not replace (multi-channel 24 bit Firewire audio interface, for instance) that no longer gets driver updates from the vendor. It goes both ways, and I don't believe it is as cut and dried as it was even a few years ago.