Operating system: Microsoft Windows 7 Ultimate Edition x64 Bit Beta Build 7000 on Compaq Preserio CQ45. User: Administrator with UAC to the minimum level. Hardware: GongTong EDGE Modem into the T-Express card slot. Trouble: Driver installation says the driver is not digitally signed and this version of Windows requires hardware drivers to be digitally signed for installation. The device driver installs but the device is reported to be NOT FUNCTIONAL in the Device Manager screen. History: I have successfully used this piece of hardware on my previous Microsoft Windows XP Professional x64 Bit without any trouble as well as Microsoft Windows VISTA Ultimate Edition. Product website: CDMA/GSM/EDGE/HSDPA/WCDMA MODEM MANUFACTURER BDC International Co.,Ltd.