If the schedule holds, Ubuntu 9.10, the Karmic Koala, comes out in the next few hours. You can be sure my downloads will be running then. I've been using Ubuntu for the past four years, and I really couldn't be happier with an operating system: it's free, it's got loads of software, and it doesn't have any viruses.
With a new release every six months, Ubuntu maintains the momentum and keeps up-to-date with the most recent developments. So while Microsoft may boast that Windows 7 came out three years after Vista, the fastest Windows release ever, all I can say is: