While Microsoft Windows Vista can automatically recognize most USB devices, you may encounter some issues with the operating system recognizing your iPhone 4 when you connect it to your PC using the iPhone's USB cable. Fortunately, Windows Vista computers support Bluetooth connectivity, so if you computer is not recognizing the iPhone as a USB device, you can force windows to recognize it as a Bluetooth device. Following these instructions to pair your iPhone to your WIndows Vista computer will force your PC to recognize it as a device.
Tap the circular button on the bottom of your iPhone to access the application home screen.
Navigate to the "Settings" application, then tap "General", and finally tap "Bluetooth". Tap the ON/OFF toggle so that Bluetooth is turned on.
Click on the Windows icon on your PC's menu bar and navigate to the Control Panel. Select "Setup Bluetooth Device" in the settings menu.
Watch for the iPhone to be recognized in the list of available Bluetooth devices that will be displayed on your computer screen. Click on "Add," which is next to the iPhone device in the list of Bluetooth devices.
Look at your iPhone's display and note that it is now prompting you to enter a four digit Bluetooth pairing code. The pairing code will be displayed on your PC's monitor.
Enter the four digit code from your PC's display into your iPhone and tap "Enter" on the iPhone's keyboard to successfully pair the device to your PC. Every time that Bluetooth is turned on in your iPhone's settings menu, your Windows Vista PC will recognize the device.