do you have any periodic / schedualed programs like virus scans / quick search / etc? have you turned the screen saver off?
sound card shouldnt be a problem because recording a audio stream uses very little audio processing power. RAM possibly could be an issue depending on of computer specs (like processer speed, what programs and services are installed / running and what operating system you're running), however even as little as 256MB would work so long as you dont have much open in the background, windows XP with the stupid themes, stupid sound schemes etc.