I have the Revo R3700 (Atom D525, 4GB). Ubuntu 64bit, with all the nVidia jazz installed and VDPAU enabled, 1080p H.264 decoding is very watchable. Watching Human Planet and Tron bluray rips skips a few frames here and there every 10 minutes, but most of the time is smooth as butter. I think some investigation and tweaking could improve things - its all playing over the network so I am wondering whether that has anything to do with it. I'm using VLC - I notice MPlayer is sometimes has better performance, so it might be flawless with that.

Anyway, I like the R3700 a lot. Definitely recommend something with ION2. I also hear that it works well with Windows.