Dropped laptop; help dianosing, backing up and fixing.

My brother, yesterday, managed to drop his laptop (Acer Aspire 5920) quite badly. Me being the 'expert' said I would fix it; I have diagnosed it and the screen is broke (£60) and I think the Hard Drive is broke (no spinning noises and on start on says 'a problem has been detected and Windows has to shut down to prevent damage to your computer. If this is the first time the you've seen this Stop error screen, restart your computer. If this screen appers again, follow these steps: Check for viruses on your computer, remove any newly installed hard drives or hard drive controllers, check your hard drive to make sure it is properly configured and check for hard drive corruption and restart your computer.' After he dropped it the problem started and ever since there has been no change, so I assume it's the Hard Drive. Also all of the problems, check for viruses' etc. can't be done seen as it is broken and won't start. I am nearly sure that all of the problems stated above are not the problem because, like I said earlier, the laptop stopped straight after it was dropped.) So next week I will be replacing the screen and the hard drive but I am not sure if the motherboard is broke or something else. Also how do I back up the pc files (inc. windows) to a external hard drive? Is it worth it or should he just buy a new laptop?

Please Help, Regards, Josh.