Extreme system Forums had a couple of threads about this a while back, and after countless benches, registry tweaks, and cache managing software, it all came back to leave it alone, and let XP manage it as it sees fit. In NTFS, there wasn't a single method to speed it up that was statistically significant (consistently over 1 percent) faster in normal usage.
I tried most all of he settings in that thread, and have to agree tha the ONLY setting that helped was to set up the drive for "file server optimized", via the memory manager tab. Even then, the performance gain was very small, and showed no real world gain except while transferring lots of files from drive to drive and trying to use the computer at the same time for something else. HD tach, Sandra, and timed data transfer between HDD's was used to test on my setup for comparison.