AirParrot works very well... I have tried it.... quality is good, but not flawless... At least on my system (Mac mini 3,1)... might vary depending on your system and video card.. In my experience, frame rate is a bit low... If you're watching YouTube videos and other standard DEF streaming media on the web then it's fine if you're trying to Stream pristine quality 1080 P video you likely won't be happy...
You know that iTunes support streaming to Apple TVs on any system you just can't do screen mirroring that would allow you to see video in the browser and things like that... But anything you have an iTunes or can convert to a format playing iTunes you can stream to your Apple TV from iTunes