You can certainly do whatever you think is best. Just think of your optical HD like a motor. You get a certain amount of miles out of it before it wears out. Defrag doesn't
hurt a drive but it puts a lot of miles on it without much benefit unless there is a lot of fragmentation. Back when drives were slower and smaller, you were using a larger percentage of the usable space it was far more necessary.
I've owned computers since the mid 80's. Trust me when I say that its a matter of
when and not
if a HD will fail. To that, I remind everyone that
"Jesus saves and so should you. Have reliable backups of anything too important to lose. " 
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Joe
See Porsche run. Run, Porsche, Run:
`87 911 Carrera