Windows Vista Search is constantly reviewing files on your system to make their contents available for quick searching.
If you keep your files reasonably organized, you don’t need this service eating up valuable processor time. With this turned off, your normal search in Windows Explorer still works fine, it may just be a second or two slower. Windows Search can really have a negative impact on system performance.
To disable this:
Click Start, then My Computer
Right Click on C: Drive
On the General Tab, Uncheck “Index this drive for faster searching”
On the next dialog box, Select Include sub folders and file.
You can also Stop and set to Disabled the Windows Search Service.