AppleCare KnowledgeBase Document:

“Some Windows-compatible computers may be able to connect to iPod (with Dock Connector) using a USB 1.1 connection, but this is not a recommended configuration. […]

You may be able to connect an iPod (with Dock Connector) model to a Windows-compatible computer using a USB 1.1 connection, but this is not recommended because the connection is too slow to synchronize music. For best performance, connect iPod to your computer using USB 2.0 or FireWire. You may need to purchase and install a USB 2.0 or FireWire card to do this.”