According to Akiba PC Watch, a short anime of Madobe Nana, an original character of Windows 7 DSP Edition, has been shown in the PC shops in Akihabara. It's a 1min long promotion video of homemade PC and T-ZONE PC shop is distributing the DVD as an extra of Windows 7 DSP Edition.

Staff
Director & Story Board: Kawaguchi, Keiichiro
Character Design & Animation: Yamaguchi Satoshi ("Strike Witches")

Cast
Madobe Nana: Mizuki, Nana
Chief: Namikawa Daisuke

Nanami is a promotional character of Japanese Windows 7 distributors, but Microsoft hasn't officially recognized her yet.

Source: Akiba PC Watch
related topic: Mizuki Nana Voices a Mascot Character of Windows 7 Ultimate

Note: Microsoft is aware of Madobe Nanami and has invited her to the official live event, but leaves her "unofficial" probably because they don't want copyright and contract problems to arise.
Source: Madobe Nanami's twitter