I want to see the performance differences between an indexed vs non-indexed column when running the same query.

The table I've created (FileCollection) is very simple and has the following 3 columns

1. Id (int) - Primary key which auto generates the number.
2. FileName (`nvarchar(MAX))` - Contains a file name.
3. Description (`nvarchar(MAX))` - Contains a description of the file.

The query I'm using is:

```
SELECT * FROM FileCollection WHERE FileName='readme.txt'

```

I've populated the database with more than 100k records. Using the `SQL Server Profiler` tool, I initially ran the query with no index on the FileName column and again when adding the index to FileName column. However, I cannot see any difference in performance.

Both tests average around the same stats:
CPU: 500
Reads: 13,000
Writes: 0
Duration: 200

Can anyone help me figure out why? I would assume 100k records is enough to show some difference but do I need more records?

TIA

Edit:
I've now changed the FileName column to nvarchar(255) but still the problem exists. BTW, I'm using SQL Server 2008 R2.