Dunno that much about stuff beyond "g" speeds. I've always been happy with "g", given that that is the standard speed supported by my lappy's inbuilt adaptor.
Most wireless hotspots are going to be "b" or "g" speeds. "n" is quite new, and being not yet fully ratified, could have some incompatibilities between different kit providers. "n" type cards should be backwards compatible with "b" and "g", so you might be more future proofed, but technology moves in weird ways
