You stated that there is no support for the Onstream USB 30 tapedrive for Windows XP. This is not correct. To get it working you have to do the following:
1. Download the Freecom USB Driver (v 1.45) from http://www.onstreamdata.com/support/downloads/index.shtml. Do NOT install the Echo software that came with your drive or the updated version for Windows XP. This software interferes with the Dantz Retrospect software.
2. Install Dantz Retrospect on your computer, before connecting the tape drive.
3. Connect the Onstream USB 30 tapedrive to your computer. First it wil ask for the USB driver you downloaded in step 1. Point to the directory where you unzipped the driver.
4. After the USB driver has been installed Windows XP will recognize the tape drive as an Onstream USB30 or DI30 drive.
5. When you start Retrospect it will recognize the tape drive.
Hope this helps you out.