|>> Do you regularly Defragment your drives to rid them of files you neither want nor need? <<|
I don't know whether this is a grammatical error or it means what it says. Defragmenting files does not delete anything. Defragmenting and deleting are two different things.
Change the 'to' after drives to 'and' and it would make sense.
However deleting files can be dangerous if you do not know what you are doing. It will not make a lot of difference unless you are getting short on disk space.
Using a disk clean-up utility like Crap Cleaner will achieve more as it will not delete anything essential to the operating of the computer.
Run Crap Cleaner first, then defrag.