Arjen might have gone direct, eliminating the mic from the equation, I'm not sure.
Also, I know jack about Windows, but on the Mac there is a control panel for sound that allows you to monitor and set the input levels going into the computer, not just the levels for the recording software. Make sure you have this level correct or it will all go to hades.
Also, the computer's preamp may not be very good, if you are just using the stock card or motherboard's sound chips. Record some simple vocals, even just speech, and see if that is distorting. If it sounds okay, try some louder volume speech, yelling even, and see if that is distorting. You may need to simply define and work within the limits of your system or consider additional equipment.
Thanks Will do
Minus Human
And all the things you said to me
I need your arms to welcome me
But a cold stone's all I see
Let my heart go
