staying connected

I just wiped HD and reinstalled XP along with sp1 and other updates. I have a dsl modem straight to pc. After initial startup i can be actively online for about 5-10 minutes tops, then it seems to stop. I release and then renew the IP and then Im active for another 5 minutes or so. Modem is in a clean area (nothing around it). A) why do I keep losing my connection? B) What can I do to stop it ?