okay 1st thing 1st.

Download :
K-Lite Codec Pack from Here
Windows Media Player 11 from Here

Install:
Windows Media Player 11 first.
and restart after successful install... (it does need validation)

and then, go to tools>option>devices>speaker:
change the speaker settings into Default:DirectSound.

Next, install the K-Lite Codec Pack....
when a lot of selection is asked,
choose no.5 1st (lots of stuff) and ticked few unticked boxes below.
(recommendation : avoid ticking on any AC3Filter box)

then, go to the next window, and ticked following preference that you would like.
including 'install additional plugins'.

in a few moments the installation should be done, and there's an option to configure ffdshows decoder for video & audio.

Configuration:
My personal taste go to 30%-50% TruBass and 25% WOW in WMP11.
equalizer stays at the default / normal...

for the ffdshows decoder video conf:
i just went to codec tab and choose any decoder for them (make sure neither codecs is disabled).
and also, activate tray icons at tray tab....

now for the ffdshows decoder audio conf.:
1st tab:
make sure every format has its own decoder (means neither should be disabled),
and regarding multiple format such as libavcodec vs libmpg etc, i would just choose them as i don't see major differences between them. enabling tray icon also one of my preferences... so that i can access it faster.

and then, the most important part:
go to mixer tab on the left., (belowmost by default)
and set as follows:
tick : normalize matrix, voice control, and expand stereo.
i don't play with the matrix or slider cause the sounds will ruin if i do so....

then. here is the most critical part i must say:
LFE Crossover tab on the left.
i would go somewhere 100-150 hz
and 2.00-5.00db gain (this is where the bass will be increased.)

feel free to tick or untick any option, but let me remind you:
if you do not tick normalize matrix, when LFE crossover enabled, sometimes loud distortion can be easily heard.
also, dolby decoder ruins my 2.1 setup.

freeverb make cinema-like effect and the echoes can be adjusted easily at its tab,
crystality provide 3D or stereo widening sound,
and FIR filter can be used to cut certain frequencies...

well,.
i think it should be quite enough, if you have difficulties accessing the menu, go to :
start>programs>K-Lite Codec Pack>Configuration>

and if you need any screenshot, i shall post soon...

(i know this is a long story, but everyone that i've shown this prove that it does enhance sound quality from my basic setup.)