Windows XP
To install the Android USB driver on Windows XP for the first time:
Connect your Android-powered device to your computer’s USB port. Windows will detect the device and launch the Hardware Update Wizard.
Select Install from a list or specific location and click Next.
Select Search for the best driver in these locations; un-check Search removable media; and check Include this location in the search.
Click Browse and locate the USB driver folder. (The Google USB Driver is located in \extras\google\usb_driver\.)
Click Next to install the driver.
Or, to upgrade an existing Android USB driver on Windows XP with the new driver:
Connect your Android-powered device to your computer’s USB port.
Right-click on My Computer from your desktop or Windows Explorer, and select Manage.
Select Device Manager in the left pane.
Locate and expand Android Phone in the right pane.
Right-click Android Composite ADB Interface and select Update Driver. This will launch the Hardware Update Wizard.
Select Install from a list or specific location and click Next.
Select Search for the best driver in these locations; un-check Search removable media; and check Include this location in the search.
Click Browse and locate the USB driver folder. (The Google USB Driver is located in \extras\google\usb_driver\.)
Click Next to upgrade the driver.
via OEM USB Drivers | Android Developers.