COMPATABILITY WITH NEW AND OLD COMPAQ PC'S

:/ :/ I HAVE AN E-TOWER 266/E-MACHINE FROM 1995 OR CLOSE TOO IT.ALSO I HAVE A PASARIO 4000 ,40GB,1.3 GHRZ PROC. 128 MB RAM.BOTH PC'S ARE DOWN DUE TOO CHILDREN.CAN YOU TELL ME WHAT PARTS IF ANY ARE UNIVERESAL (COMPATABLE EACH OTHER)AND
IF THEY ARE SAY I NEED TO THROUGH THE PASARIO CPU INTO THE E-TOWER AM I WAY OFF BASE?PLEASE ADVISE.THANK YOU.
C.J.