We have a vegan/vegetarian (hence veg*n) distribution list at work, and one of the regular topics that comes up is good sources of protein. The next-most popular topics are iron and vitamin B-12, since many meat-eaters think that veg*ns can't possible get enough of these nutrients.
It turns out that with a little research/education, and a varied diet, you can meet all of your dietary needs with a veg*n diet.
In terms of education, the Internet has lots of good information... So much that it's hard to know where to start or who to trust. I'd recommend starting with the pages on the Vegan Society website.