Hi,
The power supply is actually the easiest and less hassle-some thing to change in the computer. All in all, you just unplug everything and then replug the new one.
The one thing I have had an issue with, is the amount of power necessary ... for example, I have to replace a 600 watt power supply that is, on occasion, powering down when you turn the computer on ... I wait 30 seconds, reset the power supply and I can bring the computer up. So that would suggest (in most cases!) that I need a bigger and better power supply to cover the needs from the motherboard and all the cards and parts in the computer itself.
With a DAW, and if you have a better/separate sound card that handles the sound (instead of the motherboard's cheapie), you will probably want the extra wattage to help.
When you look at the back of the computer you might see the label of the power supply, btw, which should tell you how strong it is ... but if you have a 300W or 400W power supply, it wasn't the dust that blew it, I bet!
Have fun ...