Perfect disk has been showing that my hard drive has a large number of immovable files that are scattered about. On my XP machine, it was pretty clear: system files and pagefile that didn't take up all too much space. What is all this "extra" stuff I'm seeing?
Here's my hdd map. The black blocks are the immovable stuff. Total HDD size is 160gb
I finally figured it out. For me, a lot of the unmovable bulk was from an overgrown pagefile. So, this is what I did: Set the pagefile to clear on shutdown and restart your computer with a boot-time defrag scheduled. It will essentially knock down the pagefile to whatever size you had it originally set at (I don't know the path off the top of my head) and rearrange the pieces. If you have regular data files mixed in with the immovable patches, you'll have to offload some files to an external storage device and run a defrag. Keep doing that until the immovable files are completely free of surrounding data. Then clear the pagefile and do an offline defrag. My immovable data is now a fraction of what it used to be.