In regard to any particular process, try "Googling" the process name.
Also try process explorer. SysInternals also have a
forum where a search might often reveal a lot about some of the processes you are interested in.
How to delete any process? Usually best done by (if applicable) setting the program that calls it into existence to not start with Windows, or disabling the service (if not needed) that calls on it.
See
Black Viper- Super Tweaks for XP an extensive instructional site on how (and why) to do (and not to do) this. Many windows processes are listed on this site. It's surprising how many can be set to manual without problem.
Try
Secunia PSI (Personal Software Inspector) to assist with the monitoring of vulnerabilities due to out of date software on your system.
This will start with windows, but can be set not to.
I use
Startup Delayer to help speed the boot of the computer, while still allowing programs I prefer to run with Windows to (eventually) start. If using this, all security apps should not be delayed. Anything else - if it's not connected to the OS, is fair game.