Hi John,
Your start up can be slow for several reasons and one of them can be too many startup items, its best to keep the list to only absolutely needed ones.
Here is a detailed link on how to disable startup items-
http://www.pacs-portal.co.uk/startup_content.php
Heres a list of startup items
http://castlecops.com/StartupList.html.
If you run many memory intensive programs and ur RAM is insufficient, that can be another reason.
If ur running low on HD space or the drive is badly fragmented ( it can be if you add and delete lots of files) that can slow down the boot. Run a disk clean up, remove junk.u cud also uninstall any programs u dont need.
Run chkdsk and defragment if this is the case. Doing this regularly can help improve performance.
http://www.microsoft.com/AtWork/getstarted/speed.mspx/
and..something really vital, are u sure the system isnt infected by spyware?
Delete prefetch
http://www.tweakxp.com/article36979.aspx
Hope this helps.