My problem is this...the scenario I am in is that I create a DataTable that can have N number of columns based on what a user checks in a tree control.  I have 2 static columns then I enumerate all the checked items in one tree and those become the rest of the columns then I loop through 2 other trees checked items and those become the rows. 

So if say in TreeA "ItemA, ItemB, ItemC,ItemD" are checked, then in TreeB "OptionA, OptionB" are checked and in TreeC "SubOptionA" is checked i end up with a table like

StaticCol1  StaticCol2 ITemA ItemB ItemC ItemD

OptionA      SubOptionA

OptionB      SubOPtionA

Then the user will fill in the rest of the data by editing the cells. 

Using a DataTable this is super easy since in a non-Silverlight App I can just bind the DataTable to a grid, the problem is the perf is really bad in a regular ASP.NET app since this grid can be quite large.  I wanted to try out the perf in a Silverlight setting but am stuck trying to do something with the DataTable to get it to be usable w/the SL Infragistics grid.  I have setup a WCF service but I don't know what/how to convert the DataTable into to get it to work. 

I have tried this guys Lightweight DataTable here : http://blogs.telerik.com/vladimirenchev/posts/09-04-23/lightweight_datatable_for_your_silverlight_applications.aspx  but i get an error...The following key(s) do not correspond with the DataSource: "xxxxx". If you'd like to add additional columns, please use the UnboundColumn type.

Any ideas?