Microsoft has made available a program to analyze and decrease the time it takes to boot to WindowsXP
The program is called BootVis
Uncompress the file.
Run BOOTVIS.EXE
For a starting point, run Trace / Next Boot + Driver Delays
This will reboot your computer and provide a benchmark
After the reboot, BootVis will take a minute or two to show graphs of your system startup.
Note how much time it takes for your system to load (click on the red vertical line)
Then run Trace / Optimize System
Re-Run the Next Boot + Drive Delays
Note how much the time has decreased
Mine went from approximately 39 to 30 seconds.