Getting a microphone to work properly is one of the more annoying chores with any Windows PC. While many PCs now have jack recognition—that is, when you plug a device into the audio jack, the PC can figure out what was plugged in—that's still not a common feature.

What often happens is that the sound hardware defaults to line-level input, which may not be good enough to work with the low-cost microphones you're using. On top of that, some systems offer separate line-level input and microphone ports—but default to a single input port. So you need to bring up your sound hardware control panel and switch to microphone input. If you still don't get sound, check to see if the microphone boost, which adds a 20-dB boost to the incoming microphone signal, is enabled.

Stand alone USB microphones aren't always a solution, as they have their own problems, particularly if they need to work alongside an analog sound card. What might work better is a USB headset (microphone plus headphones). Use that to record the voice over, then unplug and work with your built-in sound hardware once the voice files have been recorded.