Driver Auto Update

Ok I managed to ****-up some of the drivers on PC - now for some of them i have the driver cd's but others are long lost....now i did back them all up using ghost-drive but upon trying to use it is asking me for a reg key and for the few times i would need it i dont fancy paying!!
Is there any free auto-update driver installers out there?
I know i could just trawl the web and find the drivers i need but is there any progs to do that for me? like you run it - it detects what needs fixed and then gets appropriate drivers???

shareware or freeware pls

v_Ln