5
You may try happy_search! With it you are free from editing PHP files like catzwolf's advice. It has google search function and is much better than xoops's default search.
First install happy_linux (framework)
http://linux.ohwada.jp/modules/wfdownloads/singlefile.php?cid=1&lid=65
Then install happy_search
http://linux.ohwada.jp/modules/wfdownloads/singlefile.php?cid=1&lid=67
Xoops Demos:
http://www.nhatban.net/info/a0021.html