Your right! Since you all seemed so determined i ripped an old dell PSU out of the attic
That's equally as bad, if not worse, than using your unbranded 720 watt...
If you look through the for sale section of this forum, you can get yourself a nice deal on a used unit.
If you are looking at a new unit with the same wattage rating as yours, it may cost between $80 and $110.
For your current system, you really do not need anything with that high of a wattage rating, in which case I would suggest what someone above already mentioned...the Corsair CX430. I've used one in a client build I've done a little while ago and they are quite solid units.