1st - Check the port settings on your router. Chances are they are auto/auto, and you'll want your NIC to be auto/auto. If possible set the ports to 100/full on the router, then set your NIC to 100/Full. Never hard set one end, while the other is look for autonegotiation.
2nd - You are troubleshooting phyisical layer crap and seem to be able to get it working. Once you got your little blinky lights, do an ipconfig /all and check to see if you're getting an IP address and all that.
3rd - If you got an IP address and default gateway configed, ping your default gateway. Do this via cmd line...."ping ###.###.###.###" The #s are the numbers for your default gateway.
If no IP address, you need to check the DHCP settings on your router....
4th - If that works, ping www.yahoo.com
5th - If that works, you are good to go and your browser is the problem. If it does not, check to make sure it resolved it to an IP address. If it did not, it is a DNS issue.
Also, ping www.yahoo.com
from your router to make sure it can ping it and resolve the address. If you can't, you need to call your ISP/replace/fix that router.