There are other (less expensive means) of getting component video down to a composite signal (and scaled appropriately from the 720p the aTV will be throwing out).
The first that comes to mind would be one of the Samsung satellite recievers... with a built in HD tv tuner, and multiple ins/outs (including a scaled 480i output via composite, that's always active, so you can drive a hi-def display and an analog tv at the same time). It's a neat little package, and the OTA HD tuner and other inputs work w/o a dish subscription.
They go for something like 60 bucks on eBay, give or take. And it will allow you to watch OTA broadcasts after the 2009 analog shut-down, if you watch anything over-the-air...