I've got a couple more questions and I should probably preface them with saying that I'm my computer knowledge is rather limited. I'm thinking of ordering an iMac and I want to take advantage of the time machine. I have a power surge protector for the cables, but a friend of mine lost a harddisk despite the surge protection (maybe it was faulty, I have no idea if this usually happens). Now I'm wondering if you use time machine with an external harddisk then it has to be permanently hooked up to your iMac, correct? So in his case, wouldn't both harddisks be fried? Is it saver to go for a wireless option? And also I'd probably have to keep the iMac in my bedroom for a couple of month while I'm moving and everything. If I shut it down every night will that harm the harddisk? How often should you reboot?