i am looking for a code snippet for building a audio spectrum analyser like the one used in winamp/win media player.Any suggestions?

This tutorial talks about using Spectrum Lab to get your data, then using Flash to display it.

http://mysite.freeserve.com/BBGorB/tutorial01.html

http://www.qsl.net/dl4yhf/spectra1.html

SpecLab gets you a datafile with the spectrum data, according to your specifications. Of course, this is not on-the-fly spectrum analysis. With this method, you need track analysis before you can display it.

Here is some VB code for on-the-fly spectrum analysis:
http://fullspectrum.com/deeth/programming/index.html

Here is an MS view on the matter:
http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/dx81_vb/directx_vb/htm/_dx_dynamic_voice_management_dxaudio.asp

You might also find something here:
http://www.planet-source-code.com/vb/scripts/BrowseCategoryOrSearchResults.asp?lngWId=1&grpCategories=45&optSort=Alphabetical&txtMaxNumberOfEntriesPerPage=10

If you were a C junky, you could use the FFT library to get your analysis.

http://www.fftw.org/