Crosmando: You know what would be a great idea? A "laptop" which looks like a laptop, as in has the monitor, keyboard and ports for peripheries, but doesn't have any hardware in it, and you could just plug a (long) HDMI cable in the back of it from your main desktop computer's GPU.
Sounds like an extremely backwards idea to me. People won't buy a non-mobile laptop hull (that even needs a monitor cable) just to be able to play on their beds. If they want to play on their beds, they either (a) move the PC to a position which they can access from their bed; that's what I did, (b) buy a gaming laptop that they can use on the bed and outside of their house; that's what most of my friends did, (c) sign up for a service that streams games to whatever screen they are currently sitting at; that's what OnLive hopes for, or (d) use a wireless mouse and keyboard, and either hook up their bedroom TV to their PC as an alternative monitor, or wait for wireless/network traffic to become fast enough to remove the need for a monitor cable; that's what technology tries to bring to households in the coming years.
Your suggestion removes the main advantage from laptops and replaces it with a niche feature that can be solved in a couple of better ways already. You do seem convinced that it would be a good solution for you personally, and that might be true - but in all honesty, as a serious product idea, it's probably the most silly thing I've heard this week.