You could wait for Microsoft's Surface computing device to drop in price so you can put one in your living room. Or you could build your own, like the guys at Maximum PC did. Even more, they documented the whole process step by step so you can build your own.
They used off-the-shelf parts, aEye , a small form factor desktop PC, and a mix of open-source software and other readily available apps to run the whole thing. The video is pretty impressive. With this data, someone could possibly beat Microsoft to the tabletop multitouch punch.
I've had a lot of experience with the Surface and I have to say it's one of the most innovative products Microsoft has come up with in years. It won't be long till the Surface--or devices like it--are everywhere. Portable multitouch devices should be arriving soon, with Apple rumored to have a 10-inch or so version readying for launch among others. Its' going to be a fun market when it blows up, that's for sure.