I have a TV in a room that can only get wireless access to my home network. Without having to drag one of my PCs into the room, what is the best (cheapest) way to watch online movies?
Assuming you want to watch online movies on the TV and moving the TV is also not a good option, here are some suggestions. You'll have to figure out what's best for you:
Run a physical cable from one of your boxes to the TV. Control the system with a wireless remote (RF or networked). iPhone wireless touch pads apps or RDP/LogMeIn/... are good solutions here as well.
Use a wireless video transmitter (RF) instead of a physical cable in the above. A little more expensive, but one less visible cable.
Use Orb on a Wii.
Get a new cheap box to use as a media center PC. Always connected to the TV and connects to wireless. Doesn't need a monitor or a whole lot of power unless you want to go HD.
If you have an Xbox 360 or PlayStation 3, then I would recommend checking out PlayOn. It's a piece of software that runs on your PC and acts as a media server for your console. You can watch Hulu, ESPN, CBS amongst other online video services. It also supports other devices if you don't have or don't want a console.