Shell Programming and Scripting

Hi. I'd appreciate if I can get some direction in this issue to get me going.

Datafile1:
-About 4000 records, I have to update field#4 in selected records based on a match in the key field (Field#1).
-Field #1 is the key field (servername) . # of Fields may vary

Code:

# comment
server1 bbb ccc ddd eee fff
server2 bbb ccc ddd eee fff # comment 3 words
server3 bbb ccc ddd eee fff
server4 bbb ccc ddd eee fff # extra comments here too
...
server499 bbb ccc ddd eee fff
server500 bbb ccc ddd eee fff # comment that drags on and on and on

Datafile2:
I have a second datafile listing identifying which servenames need an update on field#4.

Code:

server2
server4
server12
server15
....
server499

When I match this name to datafile1:field#1 to a name in datafile2, I want to change field#4 to static value e.g."444" and update datafile1.
Desired output:

Code:

server1 bbb ccc ddd eee fff
server2 bbb ccc 444 eee fff # comment 3 words
server3 bbb ccc ddd eee fff
server4 bbb ccc 444 eee fff # extra comments here too
...
server499 bbb ccc 444 eee fff
server500 bbb ccc ddd eee fff # comment that drags on and on and on and on

I'm thinking along these lines
-while Read datafile1
-move record to storage
-grep datafile2 for a match to datafile1:field1
-no match: write record unchanged
-match: alter field4 to '444' and write record

Would awk or sed suit this best?
I'm thinking awk, but can I easily contain the necessary logic to grep an external file looking for a match?

Code:

awk 'NR==FNR{a[$1];next}$1 in a{$4="444"}1' Datafile2 Datafile1

Thanks bartus11, that's exactly what the Dr. ordered.

Now I've got to go read up on FNR and get a good handle on how it works and where else I can use it.