Wireless local-area networks (WLANs) based on IEEE 802.11 a/b/g standards are growing rapidly. WLANs can provide the benefits of network connectivity without the restrictions of being tied to a location or restricted by wires. Despite the convenience of mobility, the performance of a WLAN must be addressed carefully be-fore it can be adopted and deployed in any environment. In this paper, we address the impact of various key parameters on the actual performance of IEEE 802.11g. A series of controlled experiments are carried to assess the performance of IEEE802.11g, in the presence of interferences, and finding the maximum through-put under realistic conditions. In addition the impact of co-channel and adjacent channel interferences and noises on the quality of video when streamed over WLAN is exposed. Overall, three sets of independent experiments were conducted to measure IEEE 802.11g's effective application-level throughput. The analysis results and measurement campaign provide insights into the required provisioning for 802.11g WLAN to ensure that it provides the needed coverage and capacity for the intended users..