A cursor will take forever to run on 1.5 million records. (you said this earlier, although in the last post you said 150 records) No table with this number of records should EVER be without a primary key or some other unique identifier!! GO to your boss and have him overrule the idiot who won't let you put one on the table. If necessary, put an identity field on temporarily til you clean up the records and then remove it!
I hesitate to ask, but you are doing this on a development server, right? You need to test your method on development before you affect the records in a production table of this size. I'm also concerned that you don't care at all what the other fields contain, how can you be sure you are keeping the record you want to keep if the data inthe other fields is different?
Oh yeah, if it really is 150 records, you could have removed the duplicates manually by now.