What software do I need to make a search engine?

Answer 1

You are going to need a lot of hardware and bandwidth too.

I can tell by the question, this isn't something you can reasonably expect to do. Just use Google or Yahoo. You can put it on your website too if you want.

Answer 2

Not sure I understand. Do you want to search your computer files? Or do you want to create your own search engine?

For your computer files, look at Google Desktop or Copernic Desktop Search.

To create you own search engine, you'll need a database and fields on which to search. You'll need some programming skills in SQL and some programming language (VB, PHP, etc.).