Simple way: Use the import wizard in SSMS to load the data into a temp table.

Then use a query to match up the data. If you temp table is MyStage and your regular table is Accounts, I'd run a select first

select

a.server

, a.account

, a.description

, b.server

, b.account

, b.description

from accounts a

inner join Mystage b

on a.server = b.server

and a.account = b.account

This will show you the contents of your account and staging tables as they match up. If this is right, you can update the account table like this:

update a

set a.description = b.description

from accounts a

inner join Mystage b

on a.server = b.server

and a.account = b.account

Then use the first statement to check things.

Drop the staging table when you are done.