^Seconded. Yongnuo is the way to go when you're getting into flash and on a budget. Go ahead and grab some cheap wireless recievers (YN has some and Cowboy Studios in the US also sells their own brand for cheap within the US) because, if you're looking to improve your lighting, I think you'll be back posting the same question in a week or two if you just stick a larger flash on top of your camera. On-camera flash with a good flash will give you a few more options and a bit more control that your built-in camera, but honestly, you can do so much more by grabbing a cheap light stand and umbrella while you're at it (Cowboy Studios also sells some really inexpensive ones but be warned, they are very lightweight stands and I personally wouldn't use them outdoors... I also found that I needed to modify the umbrella bracket to get the pole angled properly... but if you're in Uni on a budget, it's still a great way to go and you can make it work for you).