Will I need an enclosure with a fan?

[Psyk]

I want to put a 40GB hard disk in an external enclosure. It will be used as backup for important work so it needs to be reliable. Is it important I buy an enclosure with a cooling fan? Or will it be ok passively cooled? (the enclosure will be aluminium)

 

[Messiah Khan]

Ive got a couple of Smartdrive 2002C enclosures, and my drives actually run slightly cooler in them, then out of them. They a quite expensive, but lined with copper for better heat dispersion and are passive and very quietening(sp?).

Edit, Nevermind, I missed the external part.

 

[rpstewart]

I had an enclosure with a fan at one point and it drive me nuts, to the point of planning backups so that I didn't have to be in the same room as the PC while the disk was active.

The IcyBox style enclosures should be fine.