Recommendations on power supply wattage are inflated, because those companies know for a fact that most people are cheap and will attempt to use the weakest power supply they can. So they recommend a better one than you need, which prevents a bunch of customer complaints.
"Green" components are often low power(hence green) which means they run slower than the regular version. That's just a warning in case you didn't know that. A 2gb card would be preferable, however as long as you game at 720p a 1gb card will do as well.