802.11b has a maximum theoretical throughput of 11Mbps, but actual throughput is around 5.5Mbps (0.7MB/s). 802.11a/g have a maximum throughput of 54Mbps, with actual throughput being close to 25Mbps (3MB/s). Basically, if you're just sharing an internet connection, 802.11b should be fine. If you're transferring large files over the wireless network, though, you'll definately want to go with 802.11a/g.