Theoretical maximum on 802.11b is 11mbit/sec, on 802.11g, it's 54mbit/sec.
Having said that - you need to be aware that the actual throughput is going to be less, depending on any number of variables - your distance from the access point, any walls, etc. in between your client & the access point, other systems associated with the access point and the type of encryption used - if any.
Under ideal conditions you can expect 802.11b to deliver approximately 6mbit/sec and 802.11g, 32mbit/sec.
Please be aware that although 802.11g is backward compatible with 802.11b - a single 802.11b client associated with an 802.11g access point, can cause significant performance degradation for 802.11g clients using the same access point.