Help, cant get online... renew ip

I cant seem to get a computer online...

specs: abit nf7-s using onboard 10/100 with winxp installed... its connected to a 16port netgear router... the other computers on the router work fine...

i reformatted, installed winxp, sp1, nforce 2.45 drivers... everything works fine but i cant get online... the MCP Lan controller is working fine in Device Manager, TCP/IP is installed. I tried clicking on "Repair Connection" and it gave me a "can't renew ip error".. so i tried going into command prompt and did the usual "ipconfig /release, ipconfig /renew" and it gave a me a DHCP can't renew ip error message... i tried uninstalling the network card and installing it again and no go. I even tried using a Linksys 10/100 PCI slot card and it didnt work (so its gotta be software related).. i also tried different lan cables and hookking up the computer to different ports on the router and to the cable modem directly

any suggestions?

Check your DHCP server. It may have allocated all the addresses allowed by its configuration.