Control Window DHCP service by constantly update bandwidth usage!

I have a notepad,which having a data store into it and then overwrite by a new data every 1 second constantly.
I want to read the data (which is the total bandwidth usage of my whole WLAN)which changing every 1 second.

From here,I want to use the data to do an admission control of the LAN.
This is basically how is the idea:
1) Read the BW data.
2) Set a Bandwidth limit as reference level (eg: 1000000 Mbps)
3) Compare the BW data I read to the BW limit, if exceed the limit,I want to Pause my window DHCP service,So that client go into my LAN.
4) If the BW going below the BW limit, the DHCP service have to automatically Continue again.

Anyone can help me on that? What programming language is more suitable to use? In this case,I using Window XP as my platform. As I do some research, I realize there is a API call "service controller" can be use n this case. I am not sure on it and I don't how to deal with the API.


Thousands of appreciate enclosed here for those who willing to help me!!