I have two computers on XP, one works perfect on the same connection, one does not .. here are the differences... is there a thread on this or know issues with NVIDIA ?

I checked out the forum, and cannot find a solution .. I have AMD 64 Processor, Nvidia nforce3, XP, cable modem, and have configured to NOT use the XP FW, configured as instructed to add Gnutella access in Nvidia FW, tried different versions of LW.. anyone have a clue or pointer to get me started on fixing this .. I get 50kbs plus speeds on downloads and in 30 seconds they all go to ZERO .. but on my laptop, XP, attached to the same cable modem and NW provider, it works perfect ?????