It sounds like fair warning, though I can't think why a PCMCIA wireless adapter wouldn't work with a particular brand of computer.
It may be an issue with the mode of PCMCIA card. Many laptops have two slots, one of which will work with cards of (I think) 32 bit (?) while the other slot won't.
To be safe I'd check with the retailer on returns policy -- or just buy a USB wireless adapter.