ummmm super mario bros. i darno dude. you've got a great start to a gaming machine but your GPU is seriously letting it down. Try and get a hold of at least a 7600GT and then you'll have a chance at playing some games.
7300 isn't bad, I had a 6600 PCI-E that ran Oblivion at highest with like 35 frames you can definately play most games today, just mess with your settings, you probably won't be able to run EVERY game on highest, but most at least. Btw Intel sucks, get AMD