Hi
Only chance is to contact manufacturer to see if they have a record
Dell keep good records of their hardware which you can lookup if you know the serial number
Sometimes the number is held in the motherboard and is not easily changed but the label under neath the laptop can easily be removed or the serial number made unreadable
BUT unless the laptop has software like Prey installed it is unlikely the laptop can be located when it goes on the internet.
Only if a laptop is recovered in suspicious circumstances will its identification be checked against a stolen list
Major Laptop Manufacutures have a option to report lost or stolen laptops on their website.
Most laptops have two mac numbers one for network card and one for wireless card
http/en.wikipedia.org/wiki/MAC_address
regards
Mike Barnes