BuddyPress

It’s not the default one. I would like to use the same buddypress search and not the one that searches with drop down options of members, groups, etc…

Have a look at http://buddydev.com/buddypress/creating-the-sitewide-globalunified-search-page-for-your-buddypress-theme/

@sbrajesh, hello I gave your plugin a try, however it doesn’t account for MU blogs, or am I missing something? Will this ever be addressed in buddypress (a sitewide easy search)?

@famous, you are right about that. searching multiple blogs is too costly on database if the posts are not cached in a global table. The unified search does not includes it because most of the sites do not use any sort of global post caching, and searching the posts on a network of say more than 20 blogs will be too much for a shared server to handle. I remember there is a plugin http://wordpress.org/extend/plugins/multisite-global-search/ which does global search.
The problem is, It will put some real strain on database. if you still want to use it, you can extend the unified search with the above mentioned plugin.

hope that helps.