Success :-)! This is how it works with Win7 64bit:
1. Download SS4.3 Ultimate Rel. 2 und NETMD760 driver from here.
2. Unzip driver to a certain folder.
3. Install SS.
4. Start SS.
5. Insert a NETMD into RH1.
6. Connect RH1 to PC via USB cable.
7. You'll get a message that Windows couldn't find an appropriate driver - click it away.
8. Open Device Manager by clicking the Start button, clicking Control Panel, clicking System and Security, and then, under System, clicking Device Manager. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
9. In the list of hardware categories, locate any "Unknown Device" entry, which likely represents the device just connected - it's marked by a yellow triangle - and then double-click the device name.
10. Click the Driver tab, click Update Driver, and point Windows to the folder which contains the unzipped driver files.
11. Win7 will install the drivers. After completion you'll find NET MD device in USB-Controller category.
12. SS will show the contents of the NET MD on the right side of the screen. Now selected tracks can be transferred to PC with about tenfold speed :-).
13. Afterwards, you can save selected tracks as wav files to PC and covert them to other audio file formats with an additional program.
14. Enjoy!
Thanks again for helping.
reinhardz