DECLARE @idTable TABLE (ID int)
INSERT INTO @idTable
SELECT ArticleID
FROM   Articles
WHERE  <whatever criteria you have>

-- recordset 1 (dataSet.Tables[0]) lists all the articles
SELECT a.ArticleID, a.Headline, a.Body
FROM   @idTable t
       INNER JOIN Articles a ON t.ID = a.ArticleID

-- recordset 2 (dataSet.Tables[1]) lists all the comments for the above articles
SELECT c.ArticleID, c.CommentID, c.CommentText
FROM   @idTable t
       INNER JOIN Comments c ON t.ID = c.ArticleID

DataView dv = new DataView(dataSet.Tables[1]);

foreach(DataRow row in dataSet.Tables[0].Rows)
{
    article = new Article();
    article.ArticleID = (int)row["ArticleID"];
    article.Headline = (string)row["Headline"];
    article.Body = (string)row["Body"];

    dv.RowFilter = string.Format("ArticleID = {0}", article.ArticleID);
    foreach(DataRowView comment in dv)
        article.Comments.Add(new Comment((int)comment["CommentID"], (string)comment["CommentText"]));

    listOfArticles.Add(article);
}