First, there is advantage in forcing your port unless you setup your Router to do port forwarding. If you didn't configure your router properly, forcing your port may have some unexpected side effects.
To configure your router for Gnutella see here:
http://www.bearshare.com/help/firewalls/index.htm
http://www.limewire.com/english/content/firewalls.shtml

Don't expect the same performance from a p2p client that you get from e.g. a Web Browser. Try downloading all files you can find containing these keywords and check back after an hour or so. If they did not download, search for the same keywords again and try downloading the results again. Some files should eventualy download, - but it may take several hours up to a few days to complete these downloads because the people sharing it frequently disconnect from Gnutella when you are in the middle of a download.