Security of truncated hash functions

[Qed]

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Suppose you need a 160 bit digest.
You can choose RIPEMD160/SHA1 or a truncated version of a bigger one
(e.g.: SHA2 family).
Which solution would be safer?
Is a digest algo designed for a given length stronger than a truncated
longer one?

I googled, but I found only
http://www.schneier.com/blog/archives/2005/10/nist_hash_works_3.html
I know that sci.crypt would be a better place to ask this question, but
I don't like it.
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