I am not sure what you mean by a dropshaw effect but here are some of the default things we do for 3D and 2D charts that you may not see if your are creating these charts through code.

2D:

There is an effects collection off the chart.  We add a gradient effect to that collection once a chart is dragged on the form.

3D:

There is a chart.Transform3D.Light property that defaults to true.  If this is set to false, you may see a less appealing chart. 

 If these did not address your issue, could be explain the look you are going for.  A picture or a link to one of these good looking charts may suffice in explaining the look you are trying to achieve

http://help.infragistics.com/Help/NetAdvantage/NET/2008.1/CLR2.0/html/Chart_Creating_a_Composite_Chart_in_Code_Part_1_of_2.html

the drop shadow in that image is just an effect our documentation team puts on most of the pictures in our docs. see another example of this effect: http://help.infragistics.com/Help/NetAdvantage/NET/2008.1/CLR2.0/html/Web_WebCombo_Binding_WebCombo_to_Data_Using_LINQ_to_SQL.html

sorry if that's a bit confusing, but our intent was not to deceive.

so although the chart is capable of displaying drop shadows within its bounds, the drop shadow effect for the entire image is not a feature of the chart.  you can request a feature here: http://devcenter.infragistics.com/protected/requestfeature.aspx 

for the time being, if you want to do something like this, you can wrap the chart in a div and set a background image for the div to simulate a shadow.  one such technique is described here: http://www.alistapart.com/articles/cssdropshadows/