I presume the distance Time Machine will go back in time is dependent on the size of external hard drive you have? As in, equal space is required for the full clone, but the more over that you have the further you can go "back in time" to restore incremental conditions. I think Time Machine is very neat, but I've almost decided against using it. I have a 160GB external for back-ups, which well covers the important bits on my 120GB notebook internal, and I just don't feel like spending even a measly $100 for a larger capacity Time Machine drive. I use .mac Backup and although people have issues with it, it's always worked for me, and I've never ever ever done any kind of incremental restore. I've only used my back-ups twice, both in the case of catastrophic drive failure, in which case they saved my bacon; but in 20+ years of Mac use, I've never accidentally deleted a file or photo I needed or wanted. An e-mail or two, yeah, but typically I catch it soon enough to dig it out of the trash mailbox; or nothing so serious I haven't been able just fire off a "Can you resend blah blah blah?"