well in that case all you have to do is port foward your modem.
find out what port lime wire likes to run on and then set it in your modem. if your not sure how to do this search google there is lots of pages out there or ring the help line that should be with your modem and they can explain it over the phone to you.
you will find most things will have to be port fowarded like msn for file transfer.
just make sure you give your computer a ip address before trying to port foward other wise your ip will change to the modem all the time and it still will not work.
remember you are networking to your modem so dns gateway and ip make it all work
if you have any problems PM me and i will exlpain