On Jan. 30, the application will be available for the online PC department, and later for GPS (Global Positioning System) devices, digital photography, portable music players and so on. In opting for WPF, Fnac.com benefited from Microsoft's active support.

"Each company devoted three people to the development team," said Leprou.

Development took four or five months. Fnac.com is also keeping an eye on Vista's features, in order to win a place on the desktops of the store's 1.8 million loyalty card holders and on those of the 2 million customers of the site.

Leprou imagines that, one day, sales offers could be transmitted directly to these little applications, based on the tastes of the surfer targeted. "But the use of these gadgets only makes sense if we manage to segment our customer database," he said.

Leprou considers that developing the same widgets in Flash would have been much harder, with no guarantee of reaching the same level of functionality. The main obstacle for these innovations for now is the small number of Vista users.