I spent a couple of hours looking for idefrag yesterday, and finally came across a working copy. Didn't realize you could not defrag a disk that you were booting off so Sno Leo 911 came to the rescue. If you haven't heard of Sno Leo check it out here Your going to need a 4GB thumb drive, which can be had on craigslist really cheap. Once Sno Leo loads install idefrag 1.7.3 because that is the only version I could get to work, which worked out fine. The cool thing about idefrag is that is has different algorithms for defragging a drive. It can just lump the empty space together which I don't recommend or it can optimize the drive by putting/organizing similar files together on the drive. My cold boot up time before using this utility was ~ 2min after using idefrag it is ~ 1min 1min 15sec. Results may vary because I have never reinstalled the OS, and have been using the stock install since I got my machine in 2007 which was loaded with Tiger, and since has received all the major and minor updates. It took ~ 7-8hrs to defrag :-/ using the most optimized algorithm the program offers, and I had to repair permissions and the disk using Disk Utility after the defrag, but once that was done, boot time dramatically decreased

Did you realize you COULD or COULD NOT defrag? You can defrag a boot drive. Maybe OSX is different than Windows, if not.