What level of service do you have with DirecTV? Since you mentioned Vizio, I'm assuming that you have HD service.
The ElGato EyeTV products do not record in HD through the auxillary inputs. On SD (via s-video or composite).
If that's all you want, then perfect.
However, if you want to record in HD (720p and/or 1080i), then you need the Hauppauge HD-PVR 1212 and either EyeTV3 or StevenToth's HDPVR Capture. EyeTV3 is $80 and HDPVRCapture is $30. The Hauppauge device runs about $220, but deals are availble to bring it down to around $160 (often through Dell).
Keep in mind the hardware requirements. Recording is typically not an issue with the Hauppauge, but the playback can be taxing at the highest settings.
ft