Here, I'll makle it even easier for you:
<a href="http://kde-look.org/index.php?xcontentmode=25">System Sounds on KDE-Look.org </a>
<a href="http://www.dbpoweramp.com/dmc.htm">DBPowerAmp Music Converter to convert the sounds to .WAV</a>
<a href="http://www.dbpoweramp.com/codec-central.htm">DBPowerAmp Codec Central to get the codecs needed to do the above. Thise can also be used to convert Mac .AIFF files to .WAV</a>