You will need to find out which models of CPU are compatible with the board in yur laptop, the easiest way to find out would be to ocntact dell. Otherwise you could do some reasearch and see what other people with the same laptop have upgraded too..
or you can find out the exacct make and model of teh motherboard and contact the manufacturer of that.
this is the stats for your processor.
any other processor that uses the same bus and thermal specs and socket should be replacable. as for the graphics, odds are you won't be able to upgrade them. Most laptops have proprietary/onboard graphics cards.
you can also use the following utility to find out more information about the system and processor.
Cheers! and hope this will help.