If you have the retail version of Panther, it will work. However, the system-specific ones often won't, or won't work well, because what we call Panther is really a lot of common code and a few specific bits and pieces for specific architectures, and the DVDs that come with the systems have the bits and pieces which are specific to that system, which might not be the same as those for the system you're trying to install it on. In other words, a brand new out-of-the-box iMac and iBook will have different files. Most will be identical but not all, and the restore disks simply have that same (different) info on them. So you'll likely see some flaky behavior if you use the iBook Restore DVD on the iMac.