XP (SP2) for now, but I'll be going to Vista shortly.
Just curious, is your feed running on your primary computer or do you have a second, dedicated computer that is hosting the feed?
I run the Syracuse, NY, feed on a dedicated, older laptop that is not my primary computer. Right now the laptop is running XP and it doesn't seem worth the time, cost, or hassle to upgrade it to Vista, assuming its specs could even support Vista.