My Winamp memory usage depends a lot.
When i launch it with a playlist open, it will take about 16Mb. But when i "refresh" it (minimize and back) it will take about 1,5Mb. And when i start listening music after that, constant usage will be about 5Mb. When minimized and listening music, constant usage will be about 3,5Mb. But when "refreshing" (Open and back to minimize) during a song, it will take only about 1,8Mb. It will change back to that about 3,5Mb, when a track changes.
Edit: I use classic skin, not modern.