750 gigs. Start your defrag and go to work. It'll take for ever to defrag that much disk.
I'm really pleased with
Diskeeper in terms of efficiency (time) and quality. Highly recommneded, and
here's a review that helps explain why. Much faster than XP's built-in defragger, and a much-have for today's enormous HDDs.
The only downside to Diskeeper is the the price, but then what's your data worth...especially after spending untold hours ripping your entire collection onto your drive(s)?
I also use
SpinRite 6.0 from Gibson Research Corporation to keep my OS drive and stripped "data" array healthy. This I give my highest recommendation, especially for those who don't back-up as often as they should (like me

)
Jim