I am at the point where I need to purchase an external hard drive. I will use it to store disk images to backup my PC. I am hoping to spend $100 or less. Walmart sells a Western Digital 500GB external for about $100. But I worry about longevity of the drive. Any suggestions? Also, I read a review where one person suggested reformatting the hard drive from FAT 32 to NFTS so that it can accomodate large files. I don't even know what that means, but should I do it if I buy this product? PS...My PC has a c drive that has 194 GB free out of 224 GB. The D drive (recovery) has 995 MB free of 8.83 GB. Thank yoiu in advance for your input!