bugmenot 25 Posting Whiz in Training

Hi I"m fairly new to python and need some help with a slightly complicated programming solution. I'm trying to write a simply TCP sniffer (not a proxy!) that will sniff tcp packets coming from a specific IP and a specific port that is arriving to my local computer where the script will be running.
I'm on windows Vista and its a built in NIC card. (if that has anything to do with programming a sniffer for this)

For ie purposes:
1. the specific ip where it is coming from is
2. the port its coming in on my pc is 90210

All I want to do is create a python script that will sniff these particular packets and convert the data in it to ASCII text.. so I can then parse through it and do something with it..

I'd appreciate some help in writing this.. I've looked at twisted framework and other things.. but its a big learning curve for me. A simple example to do what I described would get me on my way much easily.

-Thanks for reading! :)