I have a computer that could easily handle Skyrim on high settings. I chose to play on the Xbox for several reasons, just as I did with Oblivion.
Firstly, I enjoy the cinematic experience. I sit on a comfy couch, not hunched over a keyboard. I dim the lights, I have the surround sound on. Say what you will about the 360's graphics capacity, the game looks impressive on my 55'' plasma flat screen. All of this adds to the immersion of the experience, for me.
When I'm on the computer, I have an ingrained need to multitask, chat, IM, check forums, play games in a window. That's fine for games like World of Warcraft, but The Elder Scrolls demands my full attention to really enjoy. On top of that, I can't trust myself not to use console commands. If I can cheat, I will cheat and the Xbox keeps me honest in The Elder Scrolls games.
On topic, seeing Helgan repaired would be interesting. The keep you go through to escape is certainly unique.