Phantom Power Circuit Comparison?
The extra circuits you have researched do not apply if all you are trying to do is interface an electret microphone to a computer mic-in port.

Those extra circuits produce a mid-rail voltage (such as 4.5 volts when using a 9 volt battery) and are useful when developing an op-amp amplifier circuit and all you have is a single power supply such as a 9 volt battery. The mid-rail voltage can be regarded as ground for any audio inputs or outputs. It is sometimes called "phantom" or "virtual" ground but I prefer the term "midrail generator" because it says what it does. You don't need this for what you are wanting to do.