These things have TOO many names, the dell manual says PC Card, everyone else calls it PCMCIA/Cardbus.

Assuming you mean PCI
uh? Laptop + PCI?

As for the universality of them, yes, they should fit. Just be on the lookout for Type I or II. The latter takes up 2 slots and might not fit. Most cards are type I though
I have a hunch that a wireless card won't be type II unless it's really sophisticated

What are you going to use it for? Wardriving? Or just general wireless connectivity?
General connectivity.

I'd agree with SirDice on the convenience of a more conceiled option rath than the sticky-outy of the usb. the only convenience of the usb ones, u can put them on a key chain, thats about it, oh, and probably generally cheaper but i could be wrong there too.
Yeah, that was my argument and I was looking around on eBay for a good deal on one and low and behold I got one for $14.37 (shipping included) :-D It's a "NETGEAR RANGEMAX WPN511" which is cheaper than the cheapest USB wireless adapter I found which was at RadioShack for about $20 + tax.

I also got a nice wireless router for $27 (My free one wasn't cutting it.) I love eBay.