How would you suggest the update to Star topology?
I would suggest for Star topology because of the following reasons.
 Less Expensive
 Nodes do not have dedicated links in between.
 One link and one I/O ports is required by each device to connect to any number of nodes.
 Star topology is easy to install and configure.
 Failure of one node do not affect the entire system. The remaining nodes work efficiently.
 There is simplicity of operations.
 It can be used for audio, video and low voltage application.

What updates you would have about network hardware in order to move to 100BaseT?
The updates are:
 100BaseT is a new technology.
 Burst rate of 100Mb/s is provided over twisted-pair.
 It supports all the network designs, rules and topologies of 10BaseT network.
 Increase in speed.
 Simple bridges are required for the connectivity.
 It can support WAN.

How would you provide the best desktop connectivity for end users, and the fastest possible throughput and security for the payroll department?
To provide the best desktop connectivity for end users we would use twisted cable to connect to the Ethernet and will bring the 8 pin cables in use.
To provide the fastest possible throughput there will be the use twisted cable which will transfer the data between nodes and devices very quickly.
To provide security for the pay roll department effective firewalls will be used at every possible end so that there is no misuse of data.
Network Diagram
The diagram of the new network would be.