Monitor Internet connections in XP/Vista

[pranav]

Hi Folks,

I am designing a project for Windows XP/Vista, one part of which is a
background process that monitors internet connections. If the user
tries to connect to any particular site, say myDummySite.com in then
some actions are taken, based on fixed policies.
This can be thought of a mini firewall.

I am sure there must be some good libraries for this purpose. I need
the names of those libraries.

Thanks,

Pranav Prakash