Try the DirectSound config tweaks
. Although not necessary close Winamp, Windows and reboot the computer after making the DS tweaks. Some have found changes don't take place untill a reboot.
Also, try updating the soundcard drivers. If you have a soundcard go the manufacturer's website for updates. If you have an on board sound chip, go to the website of your computer provider or the manufacturer of the mother board.
No luck? Please provide system and Winamp specs
as pc_guru_86 asked for.