I don't know that 23 running processes will slow you down-depends on the processes. 5 running processes will slow you down if they take awhile to complete on startup. I have 29 processes on startup, and my boot times are always very quick...
I agree that scanning for spyware would be a good start to the process of elimination, as well as a good virus scan. Your system specs might help...is your filing system FAT32 or NTFS? And how much free space do you have on your HDD?
Fat32 will need to be defragged more often, and will show a performance decrease as the drive has less free space...
Have you installed any updated drivers lately? Some drivers not digitally signed by Microsoft can cause a system to hang before booting...case in point--drivers for the Gamesurround MuseXL sound card.
There's a utility called BootVis that can help troubleshoot startup hangs...I don't have the specific link right off hand, but I know you can get a copy at kellys-korner.com
*EDIT* Here's the link for BootVis:
http://www.kellys-korner-xp.com/xp_tweaks2.htm#util
At the bottom of the page, under "Utilities for XP"