I use Sysinternals PageDefrag to ensure that my system files and page file are all in one contiguous lump. These files never usually get defragmented as they are always in use by the OS.
I second that. Defragging the paging file and system registry using the Sysinternals tools is one of the easiest speedups for an aging Windows system.
I never use the built-in defrag tool in Windows. Ironically, it skips the page file and registry (they are in use), so it doesn't give much of a speedup, and can even cause a net slowdown in certain conditions. After usage, you'll have less fragments per file, but files that go together may be further scattered from each other. Giving an overall wash and still poor overall performance where you notice it [startup, shutdown, app loading, etc].
