PCMCIA has grown up with technology over the years. At first, it was
16bit 5volt cards, the standard PCMCIA. Then PCCard became the next
standard (downward compatable), which i'm not sure what the change was
with that. Now they have Cardbus cards, that are 32bit and 3 volts.
Chances are, your wireless card is an old PCcard version (like the
Orrinco Gold I have), and the new one is a Cardbus (like almost all
PCMCIA cards made today).
Did you have trouble putting it in the slot? Like it was stuck and you
had to push it in hardder? that would be a sign that isn't not the
card to use. Look at the plug in parts of both cards, you should see
some grooves and stuff on the sides, if they don't match, then they
aren't the same.
Also, it's an hardware issue, not a driver issue. You are going to
have to upgrade your laptop to use the new cards, or if you have USB
2.0, you can get a wireless G USB (I have this nice microsoft one that
works good), but if you don't have usb 2.0 (and NO, they don't make
older cards for that, all usb cards are cardbus) then wireless G won't
work on your laptop.