I'd choose PCMCIA over USB because I have found PCMCIA network adapters to be far less troublesome than their USB counterparts. Stick to USB on desktops where you don't have a PC card slot, but on a laptop, I'd go with a PC card for ANY kind of network. You'll probably have more choices, and they'll probably be less expensive.
I'd choose Wi-Fi over Bluetooth because you are more likely to get other use out of the Wi-Fi PC card. Once you have that card, you can use it with your laptop at Wi-Fi hot spots, or when you visit family and friends who have Wi-Fi home networks. Bluetooth access points just are not as common -- Bluetooth is seeing increasing use these days, but primarily as a "cord replacement" (connecting headsets to cellphones, for example).
Finally, although you didn't ask, I'd probably buy an 802.11g Wi-Fi PC card, even if your laptop has built-in 802.11b. You will find that prices are pretty darn good for 802.11g cards these days -- either the same or just a few $s more than 802.11b. Your new 802.11g PC card will interoperate with your laptop's built-in 802.11b Wi-Fi, but at 802.11b rates. So why buy G now? It's probably a newer, better product that will be supported longer by whatever vendor you choose.
This was first published in January 2005