Search doesn’t have to be complicated. You can deliver Search to your organization quickly and easily for free with Microsoft Search Server 2008 Express.
This article explains how to install Microsoft Search Server 2008 Express with WSS 3.0.
Follow the procedure from this link Install Microsoft Search Server 2008 Express to begin the setup process. Choose the advanced option.
When the installation completes you need to configure the Search Server from the central administration site:
When you're finished with the Search Server installation you'll be taken to the configuration page.
Just follow the steps and configure Search Server.
I got an error because the search site was not yet created.. Nothing to care about.. just create the search site and then hit the ok button.
Go ahead and create the Search Center Site (Choose from enteprise templates)
After the Search Site was created:
Now go ahead and configure the Search Service:
You can add Content Sources and Scopes and start a full crawl!
Now you need to add a link to the Search Center from Home:
And from the Search Center Site back to Home:
You're finnished!
Good luck!