Congrats all of you on trying to eat vegan! It's a little hard at first but very rewarding!
I've been 75% vegan since March 10th 2011. I do still eat real cheese on occasion but only because it's so hard to avoid, especially when eating in restaurants or at friends' houses. But everything in my pantry at home is vegan, even the butter.
I did it for my health, it is a great way to drop pounds, especially for people like me who can't seem to lose weight any other way. I've lost almost 20 pounds these 3 months, and pretty much cured myself of asthma. It's great!
I agree that eating vegetarian/vegan makes a person less hungry. I've also been on a pretty strict sugar-free diet at the same time as being almost-vegan, because I was pre-diabetic, and cutting out both animal fats and sugar makes me crave less. I eat easily 40% less calories a day than I used to.
For those concerned about protein intake, definitely try tofu. It's an acquired taste but if you sautee it in a low-fat oil and toss it into some stir fry it's an awesome source of protein. Miso soup is another good tofu source. If you're new to tofu I would suggest following a recipe first, it can be a food that's easy to ruin.
Keep up the effort! I think that going vegan one day a week is great, but another way to go about it is to simply replace some of the meat/eggs/dairy you eat with vegetables/fruits/whole grains whenever you feel like it. In other words, simply trying to change your thinking to be more veggie-oriented and less meat-oriented. In that case, even if you do still eat meat you're getting more veggies.