I mean, again, if Steam were released for 360, it would likely simply be another platform for distribution of 360 games, it probably wouldn't really increase the likelihood of computer games being ported to that platform. I also doubt that Microsoft would allow it. If they chose to go in the direction of digital distribution with major titles, they'd probably just expand Xbox live marketplace, rather than allowing a third party to come in and take those profits instead. Of course, the PS3 allowed it, but Sony took a surprisingly liberal stance with a lot of issues when it comes to the PS3, a stance that Microsoft has never shown a willingness to imitate.
Also, I don't see how you'd port Paradox games to a controller. Besides, of course, having the analog stick control a mouse pointer, which is a shitty way to play a game.
S-Video is absolutely terrible quality for the PC. For one thing, you're going to be limited to 480i, and it's going to be blurry and hard to look at. A lot of games don't even allow that resolution, they'll bug out.
My laptop has a relatively good graphics card and an HDMI port. So, when I'm not toting it around, I typically just hook it up to the HDTV and use it with a wireless mouse and keyboard (the keyboard in my lap, the mouse on a tray table to my right). It is a lot more comfortable than sitting hunched up in front of the computer at a desk, or laying down with the laptop (which is basically a furnace) on my chest and trying to navigate with a shitty touchpad mouse (I never use the laptop on my lap). That's actually the setup on which I'm typing this out.