802.11 is the wireless standards that come in 3 flavors a,b,g soon to be 4 with draft n due soon. With a 802.11b adapter, you max out at 11 Mb per second. 802.11a and g both max out at 54Mb. You can get adapters that can handle all three ( maybe needed if you travel to alot of different places) but if I were buying I would get one that handles b and g. That would increase your speed.
Probably worth mentioning that even with a state of the art wireless adapter most of the time your speed is limited by the wireless router that a particular hotspot is using. That's not to say you shouldn't buy the best wireless card you can for your laptop, but if a hotspot is using a pokey old router your wireless adapter won't really help much
