I have an acoustic-electric guitar. Since I don't have a real amp yet, I'm connecting my guitar through computer to amplify the sound...
Here is my problem

: I use FreeAmp2 (
http://frettedsynth.asseca.com/freeamp2/index.html) as an amp simulation. When I turn the Overdrive on I often hear feedback (you know, that beeeep

sound that destroys

your ears). Then I have to turn the volume down, but then I hear almost nothing.
I noticed that feedback is usually high trebled.
How to get rid of that feedback? I tried cutting some frequencies like 630 Hz and 20 kHz and it helps a little.... (a little...) I heard for feedback eliminators(?). How do they work?
Anyway, can you help me, please

! I have "terrible experiences" when the feedback starts to destroy my gear.
--- I want to notice you that I'm having hard time writing English, so I'm sorry if I did some grammar mistakes. I hope you understand what I wanted to say. ---