I was a PC gamer too, until I got my Wii in April 2007 (I also have a PS3).
Here's a list of games I have currently, and notes on each game:
-Wii Sports: Of course, it came w/the Wii
-Wii Play: Got the game for the 2nd controller, a good choice to play with multiplayer, and perhaps by yourself if you have nothing else better to do, but it does get dull fast
-Super Paper Mario: Fun, descent Mario game to have
-Resident Evil 4: I really enjoyed this game with the Wii's motion controls
-The Legend of Zelda: Twilight Princess: Currently, I haven't finished this game as I am stuck at a certain point. I thought it was OK, not bad, but I found myself playing other games. As for the story, I didn't think I was missing a whole lot by not playing previous Zelda games, so I believe you should be fine if you get the game.
-Super Smash Bros. Brawl: I enjoyed the original SSB, so I got this game. It's OK-perhaps it's just me, or I should play more, but I didn't think the controls were responsive. I haven't played with other people, but I'm sure this would be really good to play w/friends.
-Mario Kart Wii: I enjoyed previous Mario racing games, so I decided to get this. I only played for one day, but I liked it. What I didn't like is (at least in single player-I haven't played with friends yet too with this title) that people behind you will get many more power-ups like blue shells to trip you up, especially if you are in first place. Of course, I'm not an expert, even when playing previous Mario Kart games, so there are probably tricks and other things to negate this.
Hope you have fun with the games you get!