The only reason I mentioned maybe getting the Gamecube now vs waiting was that Nintendo may not be giving away the free game once they drop the price of the Cube down to $99. So, if I were in your position, I would go to a store like Circuit City or Best Buy and pick up the Cube with a free copy of Zelda. Then I would head over to Blockbuster and pick up Metroid Prime(brand new) for $20. In a couple weeks when Nintendo announces the price drop you can take your receipt back to Circuit City or Best Buy and get them to price match the new $99 price, refunding you back $50. Those stores have a 30 day price match policy, so if you buy something from them and it goes on sale cheaper somewhere else or there within 30 days of purchasing it, they'll give you back the difference. In any event, then you get the Cube and Zelda for $99 and Metroid Prime for $20. So you've got a brand new system and a couple of great games for it for $120 after all is said and done. However, I'll understand if you want to wait as Nintendo may still include the free game in the $99 deal. Nothing has been confirmed yet.
As far as Metroid Prime in first person mode, I was really skeptical at first, but after playing it I have to say it is one of the best games I have played in a long while. The game was just so much fun to play and was very addicting. It's one of those games that made me anxious to get home from work so I could play some more and see what was coming next, which is a rare occurence for me. In fact, I was so hooked on Metroid Prime that after completing it I went back and looked for all the different items so I could beat it again with the best ending(yes, there are slightly different endings, nothing big though).
As far as other cube games go I think Eternal Darkness and Rogue Leader are 2 of the best games it offers and both game can be bought for $20 each. There are tons of first party games I would recommend, but you're probably already aware of a good bunch of them.
Anyway, good luck with your decision. With these price drops it is making me more tempted to get an XBOX, but I still wanna wait til there are more games out for it that I want. Although, if they change their bundle a bit and maybe include a game in it that I want, I may be forced to dive in early and get one. I've heard rumors that they plan on changing the pack in games in the bundle, so I'm keeping my fingers crossed.