If you use any software, remember to take into consideration VLANS. Most probes will not go beyond these due to MAC restrictions on ports. You also may not need to purchase expensive items to check the performances. If you do a diagram of your network and use the backbone-access method layout, you can easily see any bottlenecks. Example, if you have a graphics intensive dept, these all should be on fiber or 1Gbps connections. if you have databases for finance dept, again 1Gbps. If you have network printers and servers, all in backbone/core topology. HTH's