To be honest if you are just using the same cr*p PSU that came with a case then it is no good anyway and needs replacing with a decent make and model. Get something aorund 650W made by Enermax, Seasonic, Gigabyte, Corsair, Thermaltake etc. If possible try and get one with a single 12v rail as they are better.
Your standard ones that are supplied with cases often go down and take a lot of your decent hardware with them which can be a costly experience.