Direct from the readme.wri for Sniffer Portable 4.7.5 sp3 (I know, I can't believe I'm admitting to reading the readme in public either), here are the list of supported cards that NAI has enhanced drivers for:
Xircom CBE2 Cardbus Card
Xircom Realport Cardbus Card
Xircom Realport2 Cardbus Card
Intel Pro/100 + MiniPCI Adapter
IBM Etherjet Cardbus Card
Symbol Spectrum 24 LA-4121-1050-US & EU
Cisco Aironet 340/350 PCMCIA Cards
Lucent Orinoco Gold PCMCIA Card
Enterasys RoamAbout PCMCIA Card
Proxim Harmony, 802.11a PCMCIA card
The IBM driver works with IBM's Ethernet card.
While Mike and Owen are correct, the NAI drivers will pass up the physically damaged frames that most switches will not forward to the mirror port, that is not the only reason to use the NAI enhanced drivers. Won't do things like drop frames and not report that to the Dashboard, pass frames up in the wrong order, or my personal favorite, duplicate frames that were sent by the laptop running the Sniffer in the Decode Display. These are all things that have happened to me when running my Sniffer using cards other than the ones on the NAI list, or when I used the regular Xircom driver for my Xircom RealPort card.
Since you are buying a new card anyway, make your life simpler and get one from the approved list and install the enhanced drivers. Just don't buy it from NAI, the sticker is not worth the extra $400.
Betty
Life is better in BettyLand.