I had a thread about this a few weeks ago. It is sad you can't copy to the HD from a USB drive. I've just been ripping a new CD to the HD every time I get in the car. I've probably got a couple of dozen albums in there now.
Memory is so cheap now the 9 GB HD is really a joke -- 16 GB USB flash drive $32
Amazon.com: SanDisk Cruzer Micro 16 GB USB 2.0 Flash Drive SDCZ6-016G-A11: Computer & Accessories
Just buy one of those and use the USB port