Here's a link to a windows XP Boot analyzer, u cud check out the trial version if you want
Hope you are regular with maintenance on your system, some of the other things you could check out- updated spyware / virus scans, see if your drive is running out of space, if so, run a disk cleanup and defragment your drive. A badly fragmented drive can also be a reason for sluggishness as well as boot issues.
Couple of links on slow system troubleshooting-
cookies,pre-fetch files and temp files [not temporary internet files] to that list
I.E.,tools,options,internet options,advanced,override,set for allow 1st party,BLOCK 3rd party.
now press start,my computer,disk drive ©,documents & settings,your username,cookies [right click folder,select send to,select desktop],open cookies and only delete those you do not want/need.
start,my computer,disk drive ©,windows,pre-fetch,view,select all,file,select delete
start,my computer,disk drive ©,windows,temp files [right click folder,select send to,select desktop],open and delete everything but today's date
i'd suggest using CCleanerhttp://www.ccleaner.com/
uncheck both cookies and recycle bin BEFORE running. open options and move cookies from delete to keep,THEN anylize/run
much faster,cleaner puter