I have a computer which doesn't run. How hard would it be to drop in another hard drive.?

The answer to your question has a few different elements so, I'll start at the beginning... You will need a "recovery disc" which is typically provided to you by the manufacturer at the time of your purchase. However, some companies such as Compaq/HP DO NOT send a physical disc, instead, they create a special partition on your main (boot) drive and save a disc image to it for the purpose of recovery. Of course, this doesn't help you out much when the entire drive fails. If this is the case, you might be able to convince the hardware manufacturer to provide you with an actual install CD. (try to speak to a customer service supervisor & explain your situation to them) OK, if you have or manage to get a recovery disc, it most likely also contains your device drivers. Device drivers are small programs that tell the operating system (Windows) what kind of modem, network, sound and display cards, etc. are in the computer and are necessary in order for everything to work. Most manufacturers post device drivers on their website & you can download them once you get your computer running again. Fortunately, Windows installs generic drivers natively (just to get you started) but, some of them may not work properly so, you really do need to get the drivers that are specific to your internal hardware. OK, you have your recovery/install disc & your drivers...What to do next? Physically connect the replacement hard drive (taking note of where all cables and jumpers go) and power up the unit. Once powered up you will get an error message stating something like "no operating system found", that's OK and is to be expected since you haven't installed it yet. (BTW, reinstalling windows on an old drive is not a recomended practice as it will likely fail prematurely as well. Aditionally, a 2.5 gb drive is really too small as a typical widows install will occupy more that 1 gb by itself.) Next, open the CD drawer, place the disc in it and restart the computer (control+alt+delete) and with any luck, the computer will restart and boot from the CD. If not, you will need to go into the bios & set the computer to boot from CD (pressing the F8 key will typically get you into the bios mode) OK, once you're set to boot from CD, you can proceed... just follow the prompts, and you should be fine. Note: you can choose to create a boot partition, but for the sake of simplicity, I'm recommending that you skip that step. Also, note that the entire reinstallation process will probably take about 30 minutes to complete. once you're up and running, you will need to connect to the internet, access Windows update (shortcut can be found at the top of the start menu) and get all of the latest security patches, etc. OK, in answer to one of your other questions: If a computer has been infected with a virus, the virus IS on the hard drive itself. You can connect it to your "new" computer as a slave drive in order to extract your data, but it's imperative that you virus scan it IMMEDIATELY upon connection so that your new install doesn't also become infected. Contrary to what your brother-in-law thinks, anti-virus software IS a necessity these days and you can find a few FREE ones on the web if you don't want to purchase Norton, Mcaffee, Computer associates or Sophos, etc. Just do a Google search for "free anti-virus software" Other note: you will also need to reinstall all of the software you had before (office suite, CD burning, media players, etc.) I hope this info helps you get started... Please send me a PM if you get stuck on something or need some additonal assistance.