PC-BSD is another option for those who want an alternative to Windows but who might not be interested in Linux or Mac OS X. PC-BSD is an operating system that is based on FreeBSD and uses the KDE desktop.
Here's some of what you'll find in this PC-BSD 7.1 release:
Fixes to bugs in the Networking and Wi-Fi tools.
Fixes to bugs in Linux Emulation.
Better stability for Flash 9 for use on sites such as Hulu.
Software Updates now encompasses the old Add/Remove Programs and Update Manager tools.
System Installer now provides upgrade/repair functionality.
I had some problems getting PC-BSD running in VMware and VirtualBox.
rest here