Hve you tried to turn off DHCP and then access your router and turn off extra security features such as firewall your pc firewall should be ok and map port, ip to the box, it may help as a lot of routers are crap unless you do so ( what make is your router? ). I dont think its down to the pc more like router ahh and is your router firmware ok.
But client/server traffic is minimal for DHCP unless the lease time is set to low values? You can easily check traffic by installing a packet sniffer like Wireshark...