Best advice is to google them, most times the 1st result is the one to click on and it will tell you what it is and if its really needed.

And the only time a process will come back after a restart is if its a programme that has a "start up with windows" option, i.e windows live messenger, other processes you remove shouldnt come back

as a guide im on xp pro with live messenger running and firefox and your usual AV and firewall and im sat on 34