Have Duplicate Records, Can't Delete Extras!

I have inherited a database with no primary keys in it. :(


There are, of course, duplicate records by the "logical key", i.e., the list of columns that should have been used in a primary key, if they only had one.
 
I can easily identify when I have duplicate records using group by and having clauses.  That's the easy part.
I can identify duplicate records by "key columns" and the subset of those records that are "identical duplicates on all columns". 
 
I need to delete the "extra copies"


I can't do it by hand using sql server manager, it won't let me, because it recognizes that more than one row matches that row. 
In Oracle, I would use the pseudo-column "rowid", which would expose the internal identifier for the row.
SqlServer doesn't appear to have this concept.
 
is there another way other than creating an empty shadow table, copying all the distinct duplicate records into the shadow table, deleting all the duplicates in the old table, then copying the distinct duplicates back into the old table.