You can disable them by accessing the programs themselves and find the
startup options and change them, this is the preferred way of doing it.
You can also disable them through the registry run keys. Or you can
get a helper utility to help you. I personally like CodeStuff Starter:
http://codestuff.cjb.net/
You can visit various web sites for information as to what these
programs are, AnswersThatWork Task List is pretty good for that kind of
information:
http://www.answersthatwork.com/
Finally you should also know that sometimes (quite often) users have way
too many unnecessary services starting with the pc. You can change the
way these services start with your Services Manager. Check here for a
list of services and what they're for:
http://www.theeldergeek.com/services_guide.htm
The list is geared toward Windows XP but it's practically identical for
Windows 2000.
John