|autoexec.bat was an old DOS configuration file. It may exist on Operating Systems prior to and including NT, but it's not used in Windows XP and new Operating Systems. If present, it would actually be autoexec.nt and is not used when the OS boots. Just when the MSDos environment is started.|
Is your issue just that the system is running slow? Start by looking at the Add/Remove Programs and see what's listed there.
Also, run msconfig from the Start Run menu, and look at the Startup Tab. That will show you the executables that are running when XP boots.