Everyone has his/her(?..) personal preferences, of course...
That's right man.
I tend to stand on a soapbox, it's where I keep the beer.
The defrag aspect opinion I have is one of the few things, in puter's, I'm sure of. I've read and read about options on this subject. I eventually came to my certainty.
As to some proof, all I got is my 20 second, or so, boot (I think, been awhile since I timed it), with pgms behaving with a nice snap during the day. Of course I employ other measures that help with the boot, using CIS is one of them.
But, my opinions are with using XP. I noted you use Vista, and soon enough, I'll be using 7. I don't know how my way's will hold up on those OS's.