Assuming you already own a PC, yes, this is what you need. The adaptor plugs into the USB port and the XM box plugs into the adaptor. You will need to supply 12 volts to the adaptor. I jumped mine off of the PSU.
You then plug the line outs from the XM box to the line in on your PC. I use Streetdeck to listen to XM. I am not sure if RR will work with the adaptor, I haven't tried it.
It is possible to skip the adaptor altogether and just wire up a serial cable to plug into the XM box. Search on terms "FAQ, XM" to find out how.