Windows XP SP3, 4GB RAM, kx 3550, SB0220 - all works fine! Windows 7 x64, 4GB RAM, kx 3550, SB0220: 1. When trying to add module in DSP, or edit they properties, sometimes system hangs and hard disk is very activity. Sometimes it resolves in 2-3 minutes, sometimes its need to reset system. With 2GB ram there is no problem. 2. Surrounder+ is not expand stereo signal into quadro (in winxp it works), just play stereo into front, from rear speakers I can hear the silent. (6channels dvd's and dts,ac3 compositions is playing in quadro fine.) 3. When I am use the master mixer, after 3-4 minutes of playing music I can hear the clicks, but when I am use Wave 2/3 or 6/7 - no clicks, but only stereo, quadro not works. To resolve clicks I'm tried to increase/decrease buffers, also tried to use other settings in the buffers configuration window, but it's not resolve the problem.