Hi Guys, I'm looking to purchase a Sony CDX-F5700. It's "XM Ready", which I've taken to mean that you still need to buy a tuner and antenna. Here's where the confusion begins for me. Is a tuner something like the Roady2? I'm thinking not, because I thought the Roady was everything you need for XM. Can anybody point me towards a decent tuner? I know that there's an Alpine unit that has this built in, but as far as I know it doesn't have MP3 playback capability and that's important to me. Any help would be greatly appreciated. Thanks!