Thanks Bonnie. This worked great - with one minor change.

DataTable ResultSet = csCOSApp.ActiveProject.dsDataStore.Tables[0].Copy();

ResultSet.Rows.Clear();
csCOSApp.ActiveProject.dsDataStore.Tables[0].Select("ProductId > 0").CopyToDataTable(ResultSet, LoadOption.PreserveChanges, delegate { });
if (ResultSet.Rows.Count > 0)
{
    LoadProducts(ResultSet, true);
}

ResultSet.Rows.Clear();
csCOSApp.ActiveProject.dsDataStore.Tables[0].Select("ProductId = 0").CopyToDataTable(ResultSet, LoadOption.PreserveChanges, delegate { });
if (ResultSet.Rows.Count > 0)
{
    LoadParts(ResultSet, true);
}

I was getting "Input array is longer than the number of columns in this table.". Turns out the destination table needs to have the structure all set up. I thought CopyToDataTable would create it.

At any rate, I learned something new.

Thanks!