When installing RR, there's a checkbox you have to select to install the SIRIUS plugin when you select "RADIO" support. You must install that plugin for it to work.
Once you have installed the plugin you need to go into RRConfig and set the port and any other options you want to use in the SIRIUS radio. From that point on, any skin that has support for sirius should be able to list your stations, tune, etc.
For Streets & Trips
You need to go in the GPS settings in RRConfig and set the path to the exe (i.e. C:\Program Files\Microsoft Streets and Trips\Streets.exe), then set it to "External" for GPS option and set the GPS window Name to : Map - Microsoft Streets & Trips
After that it's just the awkward part of using all the small buttons/menus on streets & trips, but it should work.
For the computer you're running that's pretty overkill for anything I can think of, but that means you should get some very fast responses on any FE you use.