Age is not really so much of a determinant in the life of electro-mechanical devices as are environment and handling. Laptops, by virtue of being subject to somewhat more handling than desktops, have a slatiistically higher component failure incidence, but that is just the nature of the world in which the critters live. My desktops remain on, configured to "sleep" after a period of non-use, and with only monitors set to power off after a period of non-use, 24/7/365 (except for when I'm actually poking around inside the cases of the suckers). When at home, my laptops usually also are on 24/7, but configured to "sleep" after a period of non-use, then to "Hibernate" after a longer period. Honestly, I've broken more stuff than I've ever had fail.
Heres
A LINK to a list of reviews for a number of portable external hard drives, many of which have greater storage capacity than the drive in your laptop. Personally, I use both FireWire and USB portable drives, as well as both inboard and outboard optical media, IBM MicroDrive and Compact Flash of both card and key platform. And I still get caught dejectedly wishing I had backed up more dilligently. Being able to is not enough ... you have to do it, or use software that does it for you (and remember not to deactivate the software

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It is a good idea to keep crap out of any keyboard, particularly a laptop's. If serious cleaning is called for, the keys can be popped off ... its a pretty good idea to write down the order in which they go back on before you takle them off ... then the understructure can be scrubbed with electronic-and-plastic-safe-solvent-dipped Q-Tips and be blown clean and dry with canned air, but its better to not need the effort. Common transparent plastic kitchen wrap over the keyboard will keep it clean, laptop or standard keyboard, and is a lot cheaper than the also available, much sexier custom-fitted keyboard protectors. If you use kitchen wrap, be sure not to obstruct any of the cooling of the laptop.