Run your gaming PC/ tower on most laptops.....Interested?

You can do that by fiddling around with X Window for Linux or BSD systems. A way to do that for Windows would be interesting if you could do it over WiFi. But I think there are already options there.

It sounds like remoting on to the PC from the laptop to play Warcraft, say like many people have in years past to play Warcraft while at work. Because of that, I don't think all things are possible in your idea. If your laptop can only display a certain resolution, say 800x600, the PC with 1920x1200 isn't going to instantly make your laptop better.

The big question is if you have everything set up in your PC already, and it connects to your laptop via physical cable, what would the point be? There isn't anything to gain using a laptop over a PC at that point. If you wanted the mobility of a laptop to play your games on your PC, remoting on to said PC would be the way to go so you could play at work or some other place where you have wifi access.

A certain amount perhaps as you are sending commands to another machine and it's sending data back to you for displaying. There are many different tools that can be used to screen share, or give remote access. For example here I use DameWare to be able to remote on to a users computer at work. I plug in the PC name on the network and it opens a new window for me (program window) that IS their desktop. From here I can do things on their computer as if it's my own computer. I move the mouse to navigate to log them off, to log myself in, to navigate to program files and install new software. Something like this would allow your laptop to access your PC, and your PC to perform the tasks. The difference being that you are remotely manipulating the input controls via your laptop instead of the physical mouse and keyboard like when you're there.

Another tool that I've used in the past was TeamViewer. This would probably be the easiest bet for you as I believe you can set it so that your specific laptop name, or code can be used to always grant access without your PC having to first accept the session to start. Again this would then let you have control of the PC and allow you to run your CAD software on your PC, but let you be sitting say upstairs watching the football game. TeamViewer should also be free... i think.

Similarly, Skype will let you share you screen. There are a number of programs out there like gotomeeting that will allow you to share your screen with another person so they can walk you through steps of doing something. From these options however, you're only sharing your screen, you arent sharing access. (I just wanted to establish the difference between remote access and sharing screens)

Think that could be something worth looking in to for you? Again the process are run on your PC like normal, you're just controlling it remotely. The processes would run at the speed that your PC can run them, but based on bandwidth etc, the response you notice from when you click something might be slower than if you were there in person.

Yep, we use the Remote Desktop feature built into Windows and a VPN router to access our work PCs while we are away from the office.

This is a free solution that works well for accessing our work programs. I'm not sure it would be good for gaming because of latency but it should work fine for doing your CAD work on your laptop. If you are working from inside your local network you wouldn't even need the VPN router.

We also access a few of our clients' PCs with GoToMyPC. This has a monthly fee but it doesn't require any special hardware. We just have to get it installed on the computer in their office and then we can log in from the computers at our office any time we want. There are free alternatives to this too.