I have a new Dell xps 210 and the connection drops every 10-20 min 

 I have a computer downstairs a dimension 4100 with a linksys WRT54G v5 hooked to it with a CAT 5 line running into my XPS the dimension works fine I also have a laptop that works flawless

is it a setting that needs to be changed or should I be running the XPS as the main system with the modem runnin through it the dimension has XP on it does that matter?

Linksys and my ISP said everything id running normal so I am out of ideas