comes with a packing slip.. this can be used to show proof that item belongs to you and you bought it.

why do you even need a receipt? they have it in their system.

get invoice from them
and email u

email them [ur sales assistant]

call dell and state ur service tag , and say u need the invoice
worth a try

Always better to register it on your own name so that no hassle later on.

previous m15x owner here.

i clean it with compressed air, for dust in the between the keyboard keys. for other parts i use wet cloth and slowly wipe it. for the screen, i use screen cleaner and micro-fibre cloth then apply some polish for excellent gloss. for internal parts, disassemble the back cover, remove the fan and clean it with compressed air, that same goes with the heatsink but without removal.

call dell helpline during working hours. mention ur case saying that you bought the laptop from the previous owner and that you want to change the owner details and address to your name. They will ask you to give the exact information of previous owner.

http://www.dell.com/support/retail/us/en/1.../IdentifySystem

you can try here first, if not then better to call them

as for cleaning i use cottons buds and cloth

counted as.   after a year i own it, i had to sell it due to personal financial issue. but next year, im going to get myself an alienware m17x back.

as for screen polish, actually its not necessary to do that. just i share my ways on cleaning the laptop. so for screen polish step, you dont need to follow.