That's something interesting I found when I started using external keyboards on my iBook... on a PC, all keyboards share the same Caps Lock and Scroll Lock states.
(Of course, my ThinkPad has some trickery to somewhat link the Num Lock states without them being the same - turning Num Lock ON on the external keyboard does nothing to the internal's state, but turning it OFF on the external turns it off on the internal, too.)
On a Mac, they don't. (Of course, only internal keyboards have Num Lock states, and there are no Scroll Lock states, but... Caps Lock isn't shared.)
Another interesting difference between Macs and PCs in that respect... it doesn't affect me much when I'm on the EnduraPro, but it DOES affect me when I'm on something without an integrated pointing device... Often, I'll still have one hand on the keyboard, with one on the laptop's pointing device. So, I don't want to move that hand back to the keyboard for some quick shortcut, or move the other hand to the laptop... on a PC, the keyboards are seen as the same, and I can hold down a modifier key on the external keyboard, while hitting the modified key on the internal keyboard.
On a Mac, the keyboards are seen as completely independent, and modifier keys only work on THAT keyboard.