Orb is a free software-based place-shifting service that lets you access your media from anywhere over the internet. Orb runs on computers with Windows XP or XP Media Center and provides streaming access to the audio and video on the computer. It also can stream live TV if you have a tuner attached to your computer, and it provides TV listings and scheduled recordings.
Once your computer is set up to stream, you can get your media streamed in WMV, RealVideo or 3GP. That means in addition to watching your videos on your computer, you can also see them on some PDAs and mobile phones. You can also access your photos and mp3s through the service, in case you're into that sort of thing.