As a user of Windows 7 I have to suggest it to everybody I meet really. The amount of streamlining done to increase functionality and simplify even the smallest task is ridiculous.
For instance, I was just asked to help my mother scan a few pictures on her computer, then crop them on Windows XP. Pictures scanned, I had to go Start Bar > All Programs > Accessories > Paint > browse to each folder, and manually rectangular select the image and crop the white borders out, then save each image.
On Windows 7, I'd hit Windows Key > Type Paint then Enter > Open my picture > Paint now automatically selects image data so I simply press crop and save. Done.
It may not seem like much, but it's one tiny example, and took a process involving about 6 steps and reduced it to 4, while minimizing the likelihood of human error in the image editing process.
Macs are fun to play with, and Linux will always have it's place. But Windows has always had usability on it's side. At this point there is so much infrastructure built on Windows that it is nearly(and silently) synonymous with computing to the lay person.
Think about this, when you are arrested in the United States, the machine that finger prints you, the machine that takes your picture, the machine that books you, all run specialized variants of Windows XP.
It's not going anywhere, Microsoft has built infrastructure, the most valuable asset in any effort to remain dominant.
