I have Vista and I've just installed ProgDVB and clicked on various channels and all the buttons to try to make it work, but all I see is a black screen.

Internet TV channels? Try disable firewall?

I noticed that the GUI had changed a few minutes after I had installed it and the Title bar said "Alternative". I uninstalled and reinstalled the software and it is working now. I'm a bit disappointed however, I had to click on about 10 channels before I got one that didn't say "error" or just took forever to buffer. It doesn't seem there are many channels available. But anyway it works.