Do not Diaplay an Item if matches with a Condition

The following code displays a list of items in a DropdownList.  What do I need to do to NOT display an item based on a condition?

SPWeb parent = web.ParentWeb;
SPListItemCollection prodItems = list.Items;
var prods = from SPListItem item in prodItems
      where Enum.GetName(typeof(WorkgroupEnum), this.Workgroup) == string.Empty || Convert.ToString(item["Workgroup"]) == Enum.GetName(typeof(WorkgroupEnum), this.Workgroup)
     orderby Convert.ToString(item["Desc"])
      select Convert.ToString(item["Desc"]);
         _prodList.DataSource = prods;