indexing has nothing to do with defragmenting a drive.
indexing is a feature of Sherlock, called "Find By Content." Basically, the computer looks at every file on your disk and makes a really large file (called an index) that is a collection of information about every file on your computer, scanning the contents of text documents for keywords, etc (this process is Indexing). Then in Sherlock, you can select "Find by content," and then you search for stuff in the index. indexing takes a riduclously long time the first time. subsequently updating the index doesn't take as long. I do not find indexing useful (I never use find by content), so I turn it off (and disable the relevant extensions, of course).
------------------
be happy!
-mac freak