The following directions only work if you have the drivers for your soundcard that support this feature. 1. Click on the volume control ico near the clock on the taskbar. 2. Click on your audio output device's icon (probably will be speaker icon) 3. In the window that opens, selec the Enhancements tab. 4. Check the box for "immediate mode" then click apply if you want to test your settings as you change them. 5. Look for an option in the list labeled, "Equalizer" or similar. Check that, then adjust the settings in the bottom half of the window (see the picture below).

As you can see in this screenshot from my computer, this is a function provided by my sound card's drivers (my sound card was made by Realtek), so if you do not see this option, you might be using just basic drivers that come with Windows. If this is the case, look for a Windows 7 driver for your sound card from your computer manufacturer or sound card manufacturer.