I do the following before defragging every 2 months or so:
1 Run CCleaner to reduce clutter.
2 Run Ntregopt, which optimizes (compact) registry hives.
3 Back up the registry using Erunt.
4 Kill all non-essential running tasks (including browser, utilities, firewall, anti-anything stuff), based on the assumption that active files and programs can't be defragged.
5 Run Defraggler.
6 Run PageDefrag
NOTES
I've used CCleaner since way back and recently started using Defraggler -- and I've noticed substantial system (XP) and browser (Firefox) speed increases.
Correct usage of Defraggler's free space defrag options seems to contribute substantially to its overall efficiency.
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http://docs.piriform.com/defraggler/using-...pace-on-a-drive
http://technet.microsoft.com/en-us/sysinte...s/bb897426.aspx
http://www.larshederer.homepage.t-online.de/erunt/
http://www.online-tech-tips.com/free-softw...-in-windows-xp/