As far as I know, 301 is fine. 302 is the one to avoid. Here are a few articles to support the idea that 301 redirects are safe:
http://tools.devshed.com/c/a/Search%20Engine%20Tricks/301-Redirects-and-Search-Engine-Optimization
http://www.seotoday.com/browse.php/category/articles/id/477/index.php
I don’t know anything about the cgi method. I wonder how it’s different from 301?