From the FAQ section at www.pcmcia.org:
What are the different card types (Type I, II and III)?
The PC Card Standard provides physical specifications for three types of PC Cards, with additional provisions for extended cards. All three card types measure the same length and width and use the same 68-pin connector.
Because they differ only in thickness and not electrical/software interface, a thinner card can be used in a thicker slot, but a thicker card can not be used in a thinner slot. Only the mechanical size of the larger card prevents it from fitting into the smaller slot.
+==========+=========+=========+====================================+
| | Length | Width | Thickness | Typical Usage*
+==========+=========+=========+===========+========================+
| Type I | 85.6 mm | 54.0 mm | 3.3 mm | Memory (SRAM,Flash,etc)
+----------+---------+---------+-----------+------------------------+
| Type II | " | " | 5.0 mm | I/O (Modem,LAN,etc)
+----------+---------+---------+-----------+------------------------+
| Type III | " | " | 10.5 mm | Rotating Mass Storage
+----------+---------+---------+-----------+------------------------+
* While any card can theoretically be used for any device, due to their size differences, the card types each fit the needs of different applications.
Basically, the difference between type 1 and type 2 PCMCIA cards is the thickness of the card.
Often a laptop can accept 1 type 2 or 2 type 1 cards.
Of greater concern for you, is finding a NIC that has drivers for the OS on the laptop.
Another major concern is does the laptop support "Cardbus" devices?
Cardbus support is not just drivers, but hardware dependent.
I suggest looking at sites that specialize in hardware for older systems such as www.pcliquidators.com
Chas