I looked at the same problem you did. I record stuff with my tuner on my desktop (SD analog cable) and I want to watch it on my TV via wireless.
I looked at all three consoles, and none were up to the task. Actually, the best console is an original Xbox, hacked to run XBMC.
Your best options are a media extender like the Popcorn hour, or something like a sage extender. I didn't want to spend any more money on OS licenses, proprietary software, change my trusty Win XP r anything of the sort. So build a basic HTPC, with Linux running on it. Mind you I already had leftover parts (memory, keyboard, mouse, hard drive, wireless adapter) so it cot me less than 300$ in parts.
Btw, make sure you set your computer resolution properly when connecting to your TV. If your TV is 1080i compatible only, chances are that your native resolution is something like 1366x768.