You need the XM direct box to receive the XM signal with any solution you choose.(The adapters do not work with other receivers). Both solutions will work equally well with Roadrunner. The USB adapter is used in lieu of a home made cable solution discussed here in the forums. It is how the data is sent to your PC. I and several others here use the home made solution that connect to a com port on your PC with no problems. The MP3car solution is well spoken of as well and goes directly to USB. I hope this helps and if it is not accurate please correct me.