Migrate A Number Of Users To Windows Authentication

I'm looking to migrate a number of sql users to windows authentication, so I want a list of each login and for each login a list of all their roles. My plan is to write 2 WHILE loops that will go through each login and for each login the list of roles.The first Row_Number is not returning the order that I want, I was expecting results like this:

1 Aaron ...... 1 db_reader
1 Aaron ...... 2 db_writer
2 Ben ....... 1 db_reader

The first row_number used doesn't seem to use the partition.The second seems to work fine.I know I can break this up into 2 queries but I want to understand where this is going wrong.

Code used:
SELECT
ROW_NUMBER() OVER(PARTITION BY sp.Name ORDER BY sp.name asc) as UserRowNo
, convert(char(45),sp.name) as srvLogin
, 'WIN' + convert(char(45),sp.name) AS WinLogin

[code].....