You do not need a 500W+ PSU for your system. A decent 300 watt unit such as the Corsair CX 430 V2 will be enough.
It'll be a good upgrade over the current generic unit you have currently. You can always opt for even better units depending on your budget.
So there's nothing more I can do except buy a new PSU?
Actually, I was thinking of upgrading my rig in the close future so that's why I was asking for a 500W+ PSU. Any suggestions?