I just had some troubles to get adb to work together with my HTC Desire on Windows 7 64-Bit. When attaching the phone in USB debugging mode, it showed up as “My HTC” device, but adb couldn’t connect to it.
First of all, you need to install HTC Sync and the included USB drivers to get your device working normally with your computer (e.g. showing up as disk drive). Then install the Android SDK and the USB drivers package (from SDK manager) and add the following lines to the file extras\google\usb_driver\android_winusb.inf inside the [Google.NTamd64] section (before [USB_Install] around line 65):
;HTC Desire %CompositeAdbInterface% = USB_Install, USBVID_0BB4&PID_0C87&MI_01
Use this driver for the “My HTC” device. It should install, show up as “Android Composite ADB Interface” afterwards and work with adb (do an adb devices to check).