Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
If you're building a computer for a relative or friend and wish to avoid the cost of Windows 7 you might look into Zorin—the Linux OS' elements such as the taskbar, file system, start menu, and desktop all work just like in Windows. This combined with Zorin having the WINE Windows Emulator preinstalled means that the end user can install Windows programs easily.
I downloaded the ISO (around 1.14GB), burning a DVD of the ISO, and running the OS from my optical drive. The OS performed well, as you'd expect from running it from the disc. Windows emulated worked well, and although the familiar copyrighted logos are missing otherwise it looks and runs just like Windows7 for average computing tasks.
In addition to WINE Zorin also comes with Play-On-Linux.