Can I watch something that is playing on my PC in one room on a TV in another room thru Roku wirelessly?

Do you mean can you stream what you're watching on your pc to the Roku? The answer to that is Gabilan has the capability to screencast, but you'll probably not be satisfied with it as it currently is. That's the only way I know of right now, and it's in the beta phase at this point. It might get better, but it might also be a hardware limitation that simply can't be overcome (there is a significant delay between the comp and the tv screen).

Also look at PlayOn and Chaneru and Roksbox. Just a few that all do essentially the same thing.

Just to make it plain:

There are channels that can stream content from one computer to another - this would be a file. It will have to be in the right format, and there are simple tools to do this.

Now, if you wanted to stream your entire desktop to see what is on your computer screen to the roku, this has to be done with live encoding, and the h.264 format takes some time to compress, so it is very sluggish, essentially slowing your computer down to where it isn't snappy anymore.

I'm sure we will get there, but not yet.

BTW, the only way around this that I can see is to put your computer video out into a hauppague hd external box and it will externally make an h.264 compliant file, and you would have to send that back in to your computer to stream that across the network using a roksbox/playon channel.