@marialisa It depends on what kind of drive your non-working computer has. If it’s a laptop and has an IDE/SATA drive and your Asus laptop has the same type of drive (the difference is mainly the type of connector) then yes, you can try one in the other. There’s also a ton of cheap external drive enclosures that you can purchase (ebay usually has them for cheap) where you can toss the drive in the enclosure and then hook it up USB to any computer and test it out. As for new drives, again I would check ebay because you could most likely find the exact drive you already own… which should lead to less compatibility issues in the long run. If you’re dealing with a desktop computer, you can pull the drive and test it in pretty much any other desktop… or again, find a cheap external enclosure. To determine what kind of drive you have, here’s some pics to help.
IDE Laptop drive: http://bigbytepc.net/images/LaptopHardDrive
(Note the pins on the back sticking out)
SATA Laptop drive: http://www.atlantis.co.zw/images/categories/SATA%20Laptop%20Drive.jpg
(Note the L-shaped connectors, one is power, the other is data)
IDE Desktop: http://i00.i.aliimg.com/img/pb/239/322/288/288322239_960.jpg
(NOTE pins on back and MOLEX 5-pin power connector. This picture has the drive upside-down)
SATA Desktop: http://image.made-in-china.com/2f0j00ZCPTenNBcjqA/1-5-TB-SATA-Desktop-Hard-Drive-WD15EADS-.jpg
(NOTE the L-shaped connectors again, just like the laptop version. The pins on the right are just jumpers and you don’t need to worry about those most of the time.
Hope this helps you a little bit.