I recently discovered that any microphone I plug in generates the same background noise. Some helpful users on Superuser pointed me towards buying a USB soundcard/Preamp to elminate this, and I've also considered recording from my phone (sounds silly) as the phone doesn't seem to have the noise problem, but I'd require a few cables and adapters. My other ideas are buying a pocket recording with a mic in, or a Headphone to USB converter. Would any of these solutions I have come up with work?
I use an app to stream audio from my phone to the pc via WiFi (also supports micro-USB or Bluetooth) Could be a quick solution if you think your phone's good enough to record sound (mine barely is)