Works great for me and I installed it on two computers.
I have a dual core proc, 2 gigs memory and Radeon x800 video card in one computer. At first I couldn't get any video, so I downloaded the latest ATI driver and it works flawlessly now. Smooth video even on HD. I am very satisfied with it.
The second computer is a Celeron (single proc), 1 gig memory and only integrated video. Same problem. I had to download the latest display driver first. But it streams SD programs really well and it can do HD, but it hiccups a bit (but still watchable)
btw, neither computer passed the playback advisor test.
I think the main thing is to have enough memory. Make sure your computer is clean (I always get rid of all the junk that automatically runs at start up) and update your display drivers.
Oh yeah, one more thing. I have to disable my software firewall (Kerio) when I use it.