Yeah, that realtek is the cream of the crap. I'm sorry inverness but it really is garbage. It's a soundblaster clone on the cheap. At any rate, try this: double click the speaker Icon on the bottom right hand corner of the screen/options/properties/recording/now you should see a list of possible recording inputs. Select them all by putting a tick in the check boxes and click ok/now you should see a mixer window with all the possible inputs./ selct the mic input and turn the volume up all the way. Make sure that no other inputs are selected or enabled. Otherwise you will suffer the "everything I record on track one getrs recorded to track 2" syndrome. This should work. If it doesn't work, the problem is probably because you are inputting a mono source into a stereo input. If you can find a single stereo 1/8" to dual mono 1/8" adapter, this may alleviate the problem.
The bottom line is, I think, that if you want to record decent levels, you will need to invest in a decent sound card with preamps or in addition to a preamp.
Hope that helps.