User Friendliness

[Deenem]

Windows began separating the basic user from the administrator account by default in Vista, over 15 years behind Linux.

That's a security feature, doesn't change the user interface at all. (Except in Vista, UAC became a compete user interface disaster)

Windows added a firewall in 2001, over seven years behind Linux's 1994 addition of ipchains.

Ditto, security related, not user interface related.

Linux was the first operating system with x86_64 support, beating Windows XP Pro x64 by two years.

Ditto, how does 64-bit give you a better user interface?

Windows added an attractive 3D accelerated graphical interface in Vista, a full year behind Linux's XGL.

Acknowledged. The one significant UI advancement in the past 13 years.

Linux's package management system can install, uninstall, and update software from one interface. Everything installed from Apache to OpenOffice and Quake 4 may be updated with one press. Windows has nothing like this on the road map.

OK, I'll grant you that one, but hardly significant

And Linux isn't slowing down. The Xen project has added an incredible level of virtualization to Linux, with more work going into the kernels development to add enterprise ready virtualization built-in [4]. Microsoft promised built-in Xen-like virtualization in Windows Server 2008 next year, but has announced that feature has been delayed and should be available sometime after launch [1], possibly in SP1, meaning Linux will lead with built-in virtualization by at least a couple of years before Windows catches up.

Virtualisation has nothing to do with improving the user interface. It's a server feature, nothing to do with the desktop UI.