You can't do it.
When I "converted" an iTunes episode to DVD, I had my ATI AIW card output to the tv. As far as I'm concerned, it still looked pretty bad. Apple's H.264 video codec is really crappy right now, and really CPU intensive. It's worse on PC than on Mac. Because of that, even on the most powerful Windows computer I could find, the video was choppy in a number of places. The only way I see it working clean would be on a Linux box with nothing running, but iTunes software is not available for Linux.
There are no hacks either. iTunes video is protected with Apple's DRM (digital rights management) which will not allow encoders or non-Apple players to play the video.
I mean, sure, you can do it. Will you be 100% happy with it? I know I wasn't.
Another issue is that iTunes video is optimized for teeny tiny iPod video screens. On the computer and tv, it's really not so hot. It's about on par with your average torrents or usenet binaries, and that's sort of crappy.