Bootable Windows USB created on Win PC for iMac

Hi,

My uncle iMac's hard drive recently crashed. The repair and verify commands gave back an error. Only option seems to erase the current partition and create a new one, but he has files on it so I'd like to find a better solution and besides, there's no guarantee that I will be able to install a new OS on the hard drive as the hard drive seems to be causing the problem - it's clicking. When we turn on the Mac, only gray screen and loading circle come up for eternity. Googling didn't help, it seems you must either be a Genius to fix an Apple product, or fork over $400 so that Apple can again line their pockets after cheaply outfitting their Macs with a faulty hard drive that starts showing problems only past the warranty period (bought it 3 years ago). I am considering filing a lawsuit against Apple if this issue has no simple solution, with the potential for a class action suit, here in NYC. This is seriously &&^&^$^ ridiculous - my uncle paid $1800 in BestBuy for a supposedly high-quality iMac only to run into a potentially dead hard drive 3 years later. &&^& this $@$*. I told him not to buy an iMac as I never used them and had no clue how to fix them either, but after all the forums and threads I scoured, it seems NO ONE, not even Apple, has a clue on how to fix this. So I am hoping that someone here can tell me if it's possible to create a Bootable Windows USB on a Windows PC to USE ON AN IMAC, WITHOUT ERASING ALL MY UNCLE'S DATA ON IT! If it is, then please provide the instructions. Your help is much appreciated!!! Thank you!