I was using my old laptop running xubuntu for a while because the latency time of running pd on windows. My newer Gateway laptop has poor performance with the sound card in Linux, so I have to run windows on it. Before, the lowest I could get it the latency without pops was 60 milliseconds. This was very frustrating, because allot of what I am doing is real-time guitar processing and 60 milliseconds is way too slow to use. But I found a way to get it much much lower. First by using the asio4all driver http://www.asio4all.com/ with built in sound. This makes a huge difference. I have tried other asio drivers, but this one performs incredibly with pd. I cannot say how it will perform on external cards, but on my built in Sigmatel, it works great. Second, by setting windows xp to run pd at real-time priority. You do this by right clicking the pd process in windows taskmaster and setting it to real time. Doing this I can get the latency as low as I had it on Linux, and possibly lower. I haven't tried lower than 15, so I'm not sure ;) But I've played for over an hour on windows with no glitches or pops, well other than the ones I was making on purpose.
Justin Robert www.justinrobert.com