Ending Processes to quicken Boot Up

[#1]

My PC has been getting slower and slower on boot up recently and I want o disable/uninstall certain processes that are running.
When I open Windows Task Manager I am totally bemused as to what each process is.
How do I find out what the processes are and whether I can stop them safely.
Are there any other tools out there that helps you decipher all this and enable you to close things down.
Thanks

[#2]

i use system config on vista. that way you can hide all microsoft services less chance of breaking somthing then
just type config in to your start menu seach bar

[#3]

First, search your hard disk for the exact file (exe) name and path, then use Google to seach for it.  You need to check it's exactly the same one though.
Also, (not for the faint-hearted) you can edit the registry to remove executables that are loaded when the computer boots. 
Look here http://www.petri.co.il/configure_auto-starting_applications.htm for a list of the registry locations.

[#4]

the simple way is to get winpatrol from
http://www.winpatrol.com/
That will among other things show you whats running at startup  the name of the company and you can click for extra info and 99% of the time it tells you exactly what it is were it is lets you kill it etc.
It also has a option to delay loading so you can get the pc up and running fast and then load some things over the next 10 mins