The Processes tab is a list of the things running. When you close a process, it just stops running. When you start Windows again (or whatever programs that ran the processes), the processes will be started again. If you close a needed process, Windows will close and you will have to start your computer again (this is not a problem, just write down that process and remember not to close it again). Closing processes does not cause any permanent problems.
I would suggest trying some of the other processes. Explore is Windows Explorer. Iexplore is Internet Explorer (it can often slow things down).