Is your primary issue monitoring or enforcing bandwidth usage? The SNMP capabilities of the AP will tell you a little bit, but until QoS is implemented in the AP you won't be able to 'control' bandwidth allocation.
Perhaps more important, you will not be able to replicate the actual throughput of a wired network using 802.11b, which will yield a maximum data rate of about 6Mbps and is inherently shared and half-duplex.
There are several 3rd party boxes that will help you establish QoS-type service on your WLAN. We can send specifics if appropriate.
Or, you can dive into 802.11a now (nominal throughput = 54Mbps, actual at shortest range = 20Mbps, proprietary 'turbo' mode = 35Mbps, still shared, still half-duplex) if you do not need to connect handhelds or anything else without a CardBus or mini-PCI slot.
Matthew Wheeler
Blue Modal