Question: I have a blown out Power Supply that I want to replace. The spec is a 145 watts PSU and I want to buy a 480 watts PSU. Will the higher wattage be a problem? According to my old PSU, it should be replaced with 127999-001. This is from a Compaq Presario.
Answer: Adding a more powerful power supply usually isn't a problem. You said your old one is 145 watts. How old is the computer that it came from? You just need to make sure that you get the right type of power supply. Usually they are AT or ATX depending on the type of motherboard you have. If your keyboard, mouse, printer ports etc are built into the motherboard then it is most likely an ATX. If not then it is most likely an AT. The power connectors on the motherboard will be unique/different between the two.
I would take the old one out and bring it with you to the computer store so they can verify what you need.