Windows 7 Ultimate
I *finally* got Windows 7 Ultimate. I chose the Ultimate version because I live in Japan, but need to use English and only the Ultimate and higher versions support multiple languages. I did *not* like the way Microsoft implemented the language support. I had to first install the OS in Japanese, then squirm my way through the different windows and dialogs to figure out how to install English. Apple handles this problem much more smoothly when installing OS X.
Anyway, After installing Windows 7 Ultimate, I discovered that my wireless device didn`t work. Soooo, I had to reinstall my old Windows XP version, download a driver for my wireless device and then *again* reinstall windows 7. Uggghhhh.
Anyway, I am now up and running with Windows 7. The positives are it`s a 64 bit OS and I have more native support for writing in Japanese.
I will learn more about the OS from here on out. But, from the looks of things, quite a bit of changes have taken place since XP. I never used Vista, so I`m a bit behind.