Our friend Andy (known as Babgvant to many) has just posted a very, very detailed guide to setting up SageTV 7 at MissingRemote. It goes into so much detail it seems a bit overwhelming but much of that is because of the hundreds of screen-shots he included of the setup process.
I should note that several of the steps he included are good to do when you’ll be using SageTV on your HTPC, but you can skip a bunch of them if you’re just going to use an extender (HD200 or HD300) for playback. For the newbies and those wanting to give SageTV a spin this is a great guide to check out.
Guide: Installing SageTV V7 at MissingRemote
Another excellent “Getting started with SageTV Guide” can be found at Destiny’s Darlin’