Welcome to WebmasterWorld Guest from 220.127.116.11
try googleing for :
site:webmasterworld.com 301 permanent redirect
plenty of very good reading from there.
The benefits of using the 301 is that Google and suposedly Yahoo will replace the old page with the new in their index and stop trying to access it.
Google will also pass on any Google PageRank value that the old page had to the new one.
Hope this helps