Zattoo works great with Ubuntu 10.04 LTS . I tried Ubuntu 8.04 LTS which also runs it,
but I prefer 10.04 because it is faster and better with video.
Keep in mind you will need a fairly good PC or laptop to run it- dual cores are common so you should have no problems. Also remember that Zattoo uses flash decoding, which is CPU intensive compared with Microsoft Silverlight.
Best to use a good water cooler on your P.C , or a Thermaltake Flower CPU cooler.
I tested Zattoo with my laptop which is silent (no CPU fan) and it stutters slightly-
but with a decent cooler I haven't seen a problem whatsoever.
Works just as well on Windows- especially Windows 7 which runs any application better due to Windows 7 being designed to use less CPU processing power.