As written in a previous post, it seems that the official mascot for the Japanese Windows 7 has it's own theme voiced by the popular seiyuu idol, Mizuki Nana, along with an officially sanctioned OS-tan, Nanami Madobe.
The theme, only available bypurchasing Microsoft’s latest operating system, is said to be the only localised original theme to date, which can prove that even Microsoft is acknowledging the selling power of moe in Japan.
The recruitment of Nana Mizuki is not surprising considering her chart topping popularity throughout 2009, and also considering she shares the same name as the operating system (nana = 7).

The rest of the theme, including a colour scheme and voicing by top seiyuu Nana Mizuki, was quickly leaked online and is currently enjoying great popularity in what some might suspect was all a well designed piece of viral marketing from the start…but fear not, it seems the link has been distributing through a number of places that we have a link for you to download from in order to patch your Operating System with your own Anime Theme!
http://www.mediafire.com/download.php?dakjm2donht
Included are the three high resolution wallpapers that you can download from here by clicking on the images and also quite a number of sound bites to take over your Operating System!
[
Sankaku Complex]
UPDATE:
There is a one click Theme Pack that you can apply instead of doing all the manual work here! With thanks to hikky to this
http://www.mediafire.com/?yyyngymjmfj will download the engfix.themepack which will allow a one click theme install onto your Windows 7 system!
Also there is one for Windows XP as well but you would have to manually add the sound theme yourself as all the WAV files are make compatible for your system! Just by clicking the link below!
http://www.mediafire.com/?tqkdt1iyizj
Oh and two more wallpapers that are fan made!