Is it good for weight gain? Im currently 6'0" and 126 lbs. I just started going to the gym but im wondering if WiiFit would help even more. What do you guys think?

I don't think it's all that great for weight gain. All the the strength training exercises are what one could easily just do on the floor.

If you want to gain muscle, I would recommend a Gym and a trainer. Really, anything you do, as long as you do it, is going to help. WiiFit in my opinion, is to help motivate people who would otherwise skip working out. If you are already motivated (and it sounds like you are), I would just stick with what you are doing,

I have the opposite issue, I naturally have a lot of muscle, but I also have a lot of fat. I am 5'8', ~210. If I was in perfect shape for my frame, I would weight somewhere in the 185 range.

Oh, and I workout for 30 minutes on the piggy bank, and it takes me about an hour to do that workout. Just some additional info :)

What is that in Kg's?

Edit

2.1 kgs not bad :D 

 I would say it's all a question of motivation. If you have little trouble getting to the gym regularly, you'll get better results if you stick with that. But if you have a hard time staying committed to the gym, I think Wii Fit might help engage your interest.

It's about 2.2 Kg's
And Wii Fit really is not the best for weight gain. It's great at toning muscle and motivating, though. Not to mention, that when people try to gain muscle, they usually gain fat, too. Muscle helps you burn fat, but not as much as people usually gain, building muscle, so Wii Fit could be used to help balance out the difference.

 I gained 1 or 2 pounds in my first 3 days.  I'm just doing mostly strength training and eating a lot.

Not really. They have some decent toning exercises, but it's mostly stuff you could do yourself.

For actual building muscle you should go to a gym. Well for anything you should really go to a gym.

However if you can't stay motivated at the gym i'd suggest getting some free weights depending on where you want to gain some muscle mass.

Little oldschool, but effective if your motivated but not enough where driving to the gym feels like a pain.

I mean... do you want to be toned or buff? 

I'm also underweight and I have Wii Fit. Umm, I can't say much yet, I have gone up little bit in weight since I got it 6 days ago. I do the strenghening exercises. I think it's good, without it, I wouln't be motivated to get up and do these exercises. It's a good guide too, it tells you how long to hold the positions and stuff like that.

edit: as mentioned by a couple other people, it might be a good idea to try a gym or something first. 

If you want to really gain what, follow these simple steps:

1) lots of beans
2) lots of rice
3) lots of push-ups, sit-ups, pull-ups

I've done it a couple times and it happens really fast for me at least with my wacko metabolism.

Wow. Umm, losing that much weight that quickly is not actually healthy. It's not all water weight, either. You're almost certainly losing muscle mass.