@Iluviaporos - A computer power supply should also be given decent surge protection with the right kind of powerboard. My father worked with computers and he always went as far as turning them off if there was the slightest chance of lightning in the area as well.
I actually prefer to get a tower with built-in power supply, because it's more likely to fit well and it's one less part to worry about. But that's only if I can find a case that I like and that has the right power specs for the build I'm going for. You have to make sure that you don't aim too low with the ratings or you might end up without enough juice when you want to add extras later on.