While we're not recommending to average users to disable the built-in search functionality, if you really don't use it, you could save yourself some CPU cycles by getting rid of it. Over at How-To Geek (my home away from Lifehacker), we've got a guide to the quick steps to disabling the built-in Windows Search feature, but you can do it easily by simply heading into the Control Panel, searching for "Turn Windows features on or off", and then unchecking Windows Search from the list.
Once you've restarted your PC, you'll notice that the search box is gone from the start menu, and there will no longer be a search box in Windows Explorer when you're browsing through the file system. You should also note that Microsoft Outlook's "Instant Search" feature depends on Windows Search, so that will use the slower Outlook search instead.
It's definitely not a setting for everybody — and frankly this writer loves the Windows 7 search box, but if you never use it, at least now you know how to disable it. If you prefer your instructions in step-by-step format, click the link for the full guide.
How To Disable Search In Windows 7 [How-To Geek]