I've done it a couple of times and it's pretty easy if you have the patience...
Just follow the iFixit guide: http://www.ifixit.com/Guide/iMac+Intel+21.5-Inch+EMC+2308+Hard+Drive+Replacement/1766/1
@Soul started
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I've done it a couple of times and it's pretty easy if you have the patience...
Just follow the iFixit guide: http://www.ifixit.com/Guide/iMac+Intel+21.5-Inch+EMC+2308+Hard+Drive+Replacement/1766/1