Im taking out an older processor out of my friends computer, while taking it out i accidently busted off one of the sides of the stand that holds the cpus heat sink in.  so i DECIDED to continue I put in the 3 ghz pent 4 in replace of the older 1.9 ghz p4 it is socket 478.  After putting it in i couldnt get the heatsink to fit securely so I put it on just so it was siiting there by itself with nothing holding it down tightly.  I turned on the comp I heard no beeps but the comp was running however the screen DIDNT do anything, the mouse didnt turn on or anything.  So discouaged i put in the old processor and turned it on only to have it have 1 long beep followed by 2 short beeps then it sat there running and nothing happened, I really dont know what i COULD have done to it i was curious that if this DELL wouldnt let it boot up simply because the heatsink wasnt on securely enough or not? i dont know im LOST please help.  Depending on what part you busted it may be replaceable...take the broken part to a computer repair shop. They probably have a bunch of them lying around.
The machine will never operate properly like this and you risk permanent damage to that CPU by continuing.