|CardBus cards are 32 bit vs 16 bit. Physically they are the same form factor. That is, they will slide into the slot. But... The little corner of them with the notches that keep you from putting them in upside down also keep you from putting a 32 bit card into a 16 bit slot. (The opposite works, of course -- you can use a 16 bit card in a 32 bit socket.) CardBus cards are identifiable (typically) by a metal edge on the inserted end -- this is a grounding plane that mates in the socket.|
I discovered all this when I added PCMCIA sockets to a few desktop machines. They came with ISA adapters, and so (duh) were 16 bit. The only card I had handy for testing was my 100Mbps ethernet card from my laptop, which of course is a CardBus card. So it physically wouldn't fit into the desktop machines. Frustrating until I figured it out. Luckily, WaveLan cards are 16 bit -- they were the reason for getting the adapters in the first place.
Hope this helps.