Excel 2007 : Compare for Duplicate Values

[ShelbyTom]

I have a table of 4 columns of text data. There are some duplicate values in these columns.

List1 List2 List3 List4
a a f m
b c d n
c e g o
i d m c

I want to be able to identify and delete the duplicates so that I have a table of 4 columns, with unique/discreet values, so that the result would look as follows:

List1 List2 List3 List 4
a e f m
b d g n
c o
i

Is there a way to do this without a macro?
Any help would be much appreciated. Thanks

[JBeaucaire]

With your text lists in columns A:D, put this formula in F1, then copy down and across to column I:

=IF(COUNTIF($A:$D,A1)>1, "", ROW())


Then in L1 put this formula, and copy down/across to column O:

=IF(ISERROR(SMALL(F:F,ROWS($A$1:$A1))), "", INDEX(A:A, MATCH(SMALL(F:F,ROWS($A$1:$A1)),F:F, 0)))

[ShelbyTom]

Thank you JBeaucaire....your solution worked exactly as I described in my objective, I appreciate it very much. But, I guess I didn't think through my objective completely....what I really want to do is hold the list of text data in column A constant, and have the remaining data in columns in B:D show discreet values to column A and to each other:

So from this:
a b d c
b g j f
c h l g
d i m j
e j n o
f k q p
g q

To this:

a h l o
b i m p
c j n
d k
e
f
g

My bad for not better describing my objective, if you have an equally elegant solution as you did for my initial query, I'd be most grateful. Thanks.