Toshiba announced on Monday a limited edition dual-touchscreen ultra-mobile PC (UMPC) running Windows 7 that will be available for purchase from select retailers later this summer. Called the Libretto W100, it could be a challenge to Apple's iPad, suggest some critics; however, unlike Apple's single-panel touchscreen computer, Toshiba's new UMPC sticks to the traditional clamshell design found in most laptops and netbooks. Toshiba did not announce pricing for the W100.








