Is your version of Windows 7, Retail or OEM? If it is Retail, you just install from the disk you have and it will most likely give you a phone number to call if the online way does not work. If it is OEM you will need to purchase a new copy of Windows 7.
The Network Card, is just a more powerful dedicated network port, so that your streaming has less lag, ess. good if you are a online game player.