You'll likely be able to boot with that disk, but the installer won't run. It will give you a message like: this software cannot be installed on this computer.
If the disk is grey, then it can only be used on one Mac model, and must be the same exact Mac model that disk originally shipped with. For example, there are approximately 11 different installer DVDs for MacBooks only. So, a random MacBook would need one of those 11, and the other 10 would not install. And, that's just for MacBooks. Some of the DVD sets will be identified for MacBooks, but most say only Mac OS X, even though they only work on a MacBook.
If you want a non-specific OS X installer, then you need the commercial DVD, which will usually be black with a big X on the label, until Snow Leopard, which is white with a SnLeopard on the label.