Now lets analyse this. You say the you have no issues till step 10.
So I assume:
1. That your ethernet connection is working fine. (Is it shown Active as in Step 5 ?)
Probably you can try these things :
1. since you are not using your onboard ethernet card you can goto BIOS and disable it. Try doing the entire process as explained on http://hemenkapadia.somee.com/tutorial/html/rhnet.asp
2. If this did not work then.....Verify that in step 7 you have selected the correct ethernet device
3. Or check if there are any driver related issues for the ethernet card (new one) that you are using.
....And still if it does not work.....
4. Post a message here with additional information...and we will try again....