Each ethernet device (the onboard NIC and the NIC card) will have their own IP address. Unless your internet provider allocates more than one IP address to you, you will not be able to use both NIC devices simultaneously with the same provider. If you had two internet providers, or two separate accounts (two IP addresses) with one provider... maybe that would work... but, I wonder how each instance of your browser would "know" which NIC IP address to use.