Does defragmenting in Windows.....

kill your datas? or crush your PC? I do defragment sometimes but I'm so scared each time I do it. So please tell me the answer. Because my external hard drive is being quite slower then usual nowadays, I think I have to defragment the ex hard drive. Or is there anyother solution??

You guys ever hear of a defragmenter that uses RAM as a buffer, instead of a disk? It'd be totally unsafe to use in anything but a a laptop or a machine running off a UPS, but I'd think it'd be a lot faster. Ever hear of anything like that?