Like you, I was almost exclusively a PC gamer before I got a Wii. You absolutely have to get Metroid Prime 3 if you like FPS games, it's a great game and it will show you how immersive Wii controls can be when done right.
If you need a second Wii remote, get Wii Play (it includes a remote), you'll have some fun too.
My Mario Kart Wii friend code: 2707-1866-0957