For taking things out:
Disconnect power & all of the cables.
Ground urself touching a metal surface.
Take the cover out, check the link u got posted before http://support.dell.com/support/edocs/systems/insp580/en/sm/index.htm
start taking out RAM sticks, & expansion cards if any.
Here after, u'll need to disconnect wires & even use screwdrivers for some components:
Take the drives out.
Take the heatsink/fan(s) out.
Take the Power supply out,
Take the Motherboard out (then compare the screws' layout with the one on ur other chassis... some Dell models like Optiplex have a different layout, they won't fit in any ATX chassis unless u mod the later, I don't think this one's like that, but u better make sure)Don't take the CPU out of its socket for any reason
. U better leave it in all of the time. U might want to clean it out & change thermal grease though.
Intall Power supply first, then MB, coolers, drives, cards, RAM & plug things in... Enjoy!