I tried that to see what my system would be returned to. Things I had turned off in msconfig were now on & some other minor changes. What else it did I don't know as I restored my system using a backup.
Sp2 increased my boot up / shut down time but only by 20 seconds or so.
Have you tried turning off unneeded things in msconfic to see if that improves your boot time?
Please note that Bootvis.exe is not a tool that will improve boot/resume performance for end users. Contrary to some published reports, Bootvis.exe cannot reduce or alter a system's boot or resume performance. The boot optimization routines invoked by Bootvis.exe are built into Windows XP. These routines run automatically at pre-determined times as part of the normal operation of the operating system.