Finding a 802.11g card that meets your requirements would be very difficult. There are very few cards with external antenna jacks, and few of those work natively in linux. I would get a good linux-compatible card without a jack and then solder
one on if I must use an an external antenna, as there aren't many with jacks to begin with.
As for 802.11b this is easy, there are many good cards with antenna jacks:
orinoco classic gold/silver (the new ones don't have jacks)
Senao/Engenius SL/EL/NL 2511CD+EXT2
See these pages for a list of good 802.11b cards: