Computer help needed due to lightening strike

Depends on the computer. Many nowadays are built into the motherboard. You'll have to go into "control panel" or whatever Microshi$ calls it nowadays and disable it, then install your new one. Depending on your computer and how "generic" it is, an off the shelf ethernet card may work, or you can get them that plug into an USB port as well.

Actually, if you're running XP or Windows 7 (and even the waaaay old Windows 2000), no need to disable the existing network connection. These OSes are smart enough to detect that the old NIC is no longer connected and will sense that the new one is active.

If you're running Vista by any chance, I recommend getting a whole new machine with Windows 7. Vista blows!