How to accomplish this task?

I have a csv file which contains two columns of data of about 300 records.
The first column of the csv is the key.
I would like to update the value of second column of csv into table Table_A in SQL Server 2005
using the query below:

update A
set A.Value2= CSV.Column2
from Table_A
inner join
(
...
...
) CSV
on A.Key=CSV.Column1

How can this be done?