Slight delay when playing sounds

I have a 933 mhz Dell Dimension 4100 with 512 MB of RAM, with a cable modem. Whenever I'm on Internet Explorer or AOL or Winamp or any other program, my computer slightly halts whenever a sound has to be played. For instance, since I'm usually signed onto AOL Instant Messenger, whenever a Buddy signs on or off, a sound effect gets played. That sound effect causes my computer to halt for about a second. What will happen is my computer will stop -- the mouse stops moving and nothing works. Then the sound plays (which is a fraction of a second long), and once it's finished playing, the computer goes back to normal. Is there any way to correct this? Even though I have a lot of RAM, I don't run a lot of programs at the same time, and my Taskbar is very clean. Thank you very much for your help.