If you are faced with Windows XP slow startup issues, there are a number of things you can do to isolate the problem and troubleshoot it, such boot up your PC in safe mode to see if you can isolate which application or device driver may be the source of the bottleneck or play around with the programs being executed in the Windows Startup menu folder.
One other thing you can do is see if there are any programs running in the Windows registry under the following folder:
HKEY_LOCAL_MACHINE SOFTWARE Microsoft Windows CurrentVersion Run
A little known secret that alludes the average, everyday Windows user is that in addition to the Startup menu folder in your Start menu, you can also specify programs to launch at boot time in the above location in the Windows registry. This is typically reserved for applications that should apply to every user and not be restricted to specific users. You should check here for any problematic applications that are being run at start up that may be causing your Windows XP slow startup issues. If you find something here that you do not really need to be startup at boot time, then you can delete those entries from underneath this registry key.
Finally, if you are still unable to identify the root cause of your Windows XP slow startup, then your next step should be to perform a scan of the Windows registry. If any errors are detected, they should be repaired. Plus your registry should be optimized for faster searching as well.
It is very likely that Windows is taking a very long time to load because the registry may need to be repaired and optimized, as the operating system reads from the registry during start up.