Free operating system for home pc

[sunghero]

                    I would  like to find an open source operating 
system to use for a personal computer. I have "WindowsXP" now, but I 
feel I'd be at home with something at least a little in tune with my 
personal philosophy, which "microsoft" is not.. Can anybody tell me if 
there are any free open source versions available ?  The computer I use 
is a simple e-machine with a celeron processor (1.4ghz).
                                                                                                          
Thank you,
                                                                                                                         
Frank