>I have a table that contains a lot of items in the Statistics node. I see in there all my indexes. However, on top of them, I also see a node with _WA_Sys_00000078_4707859D as the entry. I can see in the Property sheet that this is pointing to a field of my table which is not an index. Can someone tell me what this means and if specific tasks would then be recommended for such a situation?

SQL Server would create statistics for columns that don't have indexes if the query optimizer decides that it may speed up queries. It may also indicate that index on such column may be beneficial. It's better to let the SQL Server optimizer create statistics to improve quieries performance.