Raul Maristany wants to add WiFi to an aging laptop. Is it possible?
If the laptop has a PC card slot, it should be able to take a wireless PC card. (If the laptop is old enough, the slot may be called PCMCIA — and no, that didn't really stand for People Can't Memorize Computer Industry Acronyms.) However, you should check the requirements for the card before buying it. Modern cards may require more powerful hardware than your old PC.
The drivers are another issue. I very much doubt that any card made today has Windows 95 drivers. Or even Windows 98.
That doesn't mean you can't find such cards. Google wireless pc card and your version of Windows, and you're likely to find some very promising hits. For instance, as I write this, Amazon.com still has two of these in stock, and they're not even used. This is obviously a model that's no longer being made ("Supports Windows 95, 98, Me, NT, and 2000"), but the price is good.
You may have to downgrade your router's security to work with the old card — see your router's manual for instructions. There are dangers to this, of course. If they make you uneasy, use Ethernet at home, and WiFi only on unsecure, public networks.