need .dll file help

hi everyone,

i wanna know the name of the particular .dll files in the system32 folder which are responsible for the followings:-

1)windows boot image
2)windows start button in the toolbar
3)windows login screen
4)windows startup sound
5)the my computer icon

is theres any way to replace this original .dll files from the system32 folder with d modified one????
becoz i wanna replace these images an icon with some different icons n wallpapers n also d startup sound.
plz give me the command lines to.plz


any help will be highly appreciated