I had meant to comment that you can also get these from Amazon.

For the USB to serial cable, I'd try and get one with an FTDI chip (just be wary of clones that claim to use these chips) as the drivers are available out-of-the-box for Windows. Null modem cables (that attach to the USB to serial cable to the 818) are difficult to get wrong, so I'd be less concerned about those.

Prolific music listener / Hi-Fi addict!