The content available to personalize the latest iteration of the Windows client from Microsoft has evolved with the addition of a new theme. The Redmond company is offering a variety of free Themes and Wallpapers for Windows 7 on the Personalization Gallery hosted on Microsoft.com. The items offered as free downloads to end users have already been refreshed when Windows 7 hit general availability, more than a month ago, on October 22nd, 2009. However, it looks like the software giant will continue to be expanding content and an illustrative example in this regard is Twinkle Wish.

The free Windows 7 RTM “Twinkle Wish” theme resulted from a collaboration between Microsoft and Saks Fifth Avenue. Designed for children, the theme is based on Saks’ holiday children’s book, “Twinkle, Twinkle Little Flake,” the Redmond company revealed. Microsoft has worked together with Saks in order to upgrade the store’s windows with Windows 7, but also to have its latest version of Windows powering experiences across the retail outlet on Fifth Avenue in New York City.

“Shoppers who can’t be in New York City this year can still participate by downloading a special Windows 7 holiday theme pack featuring Twinkle and some of the key scenes from the book at the Windows Personalization Gallery,” Microsoft noted.

Windows 7 users that have already visited the Personalization Gallery have undoubtedly noticed the variety of brands featured on the page. Microsoft is offering free themes with content from Ferrari, Porsche, Pepsi, Ducati, and now Saks. The Redmond giant explained earlier this month that the free custom themes for Windows 7 were the result of various companies worldwide using the operating system as a vessel for brand advertising.

Microsoft Advertising is running a pilot program scheduled to last until at least October 2010, in which Windows 7, via the Windows Theme Experience and Windows Personalization Gallery, is made available to companies for brand interaction with consumers. Saks Fifth Avenue is just the latest Microsoft Advertising partner to take advantage of the Windows 7 in order to put its brand on users’ desktops.