Processes means the active programs running. These include essential XP parts such as explorer. You know when that has a problem in that all you end up with is a mouse pointer and a wonderful desktop background. But there are also lots of useless things too.
I have 33 processes running at the moment but I am multitasking also. However considering you make no mention of what spec of computer you are running I would guess that it may be a bad idea to suggest you do very much more than in the little box with the clock in the bottom right disable some of the rubbish that starts there.
Common annoyances are Microsoft office and or word, winzip, any graphics utilities such as ATI or nvidia panels, also gems such as quick time, itunes, music match and other media players love to reside there. Just disable everything loaded there except your antivirus and firewall. Right clicking or double clicking often will bring you the options to disable them.
Also clear out the Start > all programs > start up folder of anything you dont need to start when your PC does. This will greatly improve how your PC responds.
Finally do a full Antivirus sweep as well as a full spyware sweep. If you dont have either I advise you get AVG free (free just google it) and also spybot search and destroy (again free just with a google) and spyware blaster. I find these 3 do the best job for most users.
Finally make sure your windows install is up to date start > all programs > windows update.
If you wish to do more and have little knowledge about the underbelly of your computer then I would advise you make a complete and up to date back up of your computer before tinkering with it.
If you want more help let us know however what I outlined above should be enough for the average user. I hope it helps