Just how much protein really?

It's so easy to feel swamped by reading too much on the net, where different sites seem to conflict each other.
 
One site for example, http://www.skinnybulkup.com/ suggests that for bulking, you should eat 1.5g of protein per bodyweight to add mass.
 
So someone weighing 100kg would need approx 150g daily.... Is this enough?  Some other sites seem to say the same person would need nearly 250g!

Research supports 1g/lb or 2.2g/kg.
 
There are a number of factors such as age.  Generally someone who is older may benefit more from say 1.2g/lb if bodyweight more than one.  Someone who's younger and newer to training should get away with 0.8g/lb of bodyweight.
 
But 1g/lb is sufficient.

weebl

So someone weighing 100kg would need approx 150g daily.... Is this enough?  Some other sites seem to say the same person would need nearly 250g!

 
The general idea of the 1-1.5g is per pound not kg, hence a 100kg (220lbs) x 1.5 is 330g protein per day. I think its about right but its not set in stone, certainly people like Dorian Yates and Chris Aceto tow the 1.5g per lb of bodyweight line. at 102kg (226lbs) I like to eat around 350g protein a day, so I tend to go a little higher.
 
If your just putting your first diet together a good way to go is with 1.5g protien per lb and 2g carbs per lb, see how you go and modify if required.