Honestly, I'd recommend an external enclosure. The price of one of those 
plus a single HDD may outweigh the cost of an all-in-one external drive, 
but once you start using multiple HDDs with it (labeled properly, of 
course), it goes down in cost significantly. The AMS Venus line [0] is 
particularly good from my own experience, and they offer models with IDE 
or SATA, USB or Firewire or eSATA, and combinations of the 
aforementioned. Considering the sizes of the drives, they are 
externally-powered, but you get the benefit of a fan that moves air over 
the drives to prolong their lives. Highly recommended.

-David

[0] 
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=50001671+40000092&Manufactory=1671&SubCategory=92&SpeTabStoreType=0

Robert Holtzman wrote:
> On Tue, 8 Jul 2008, Bear wrote:
> 
>> Did you mean 3+Tb?
>> If you really meant 3+Gb then pretty much any external enclosure
>> supporting mirroring should be fine and give you 100x the space.
>> did you mean reliable or durable?
> 
> Sorry,typo. I meant 300+Gb. Also, I meant reliable, as in decent quality 
> without a lousy record of failures. This is to use for backup medium.
>