Hello, I have been running FSK since 1971. Aftern reading notes from Don, AA5AU, relative to FSK'ing on USB, I bought a F5U103. As Don has mentioned, it FSK on my XP. Rick W4UEF It seems that the Belkin F5U103 does not work with WIN XP, at least the ad's leave one to believe that. Has/does anyone use one with XP ? Tnx, Dick, W1KSZ