Hello & Welcome to JustAnswer.
This is changed in Windows 7 and the later versions.
In the lower right corner, there is a sound icon.
Right click on this icon, and then select "Open volume mixer" - this will list the options depending on your card/driver.
Further settings can be accessed by:
Right Clicking the same sound icon, and selecting "Playback Devices" / "Recording Devices", this will take you into the properties for each from where you will get further controls.
But by default, it is already set to work at it's best and i would not suggest changing anything there unless you really need to.
You can still raise/lower the volume which is okay.
But if you still want to have extra controls, then you can download an equalizer from http://sourceforge.net/projects/equalizerapo/
Let me know if you have any questions and if i have answered your questions, then please remember to rate my service by clicking the star icon.