need help with microphones

hi...im looking to buy a microphone for voice overs and the occassional freestyle rapping we do for fun...right now i dont own a camera..(its my friends)...and the audio sucks badly..i need a microphone that can plug into my soundcard and actually sounds good....anyone know where i could get a good one and not some crappy 3 dollar one....and if there is some other thing that records sound good that doesnt plug into computer like some sythensizer thing or something tell me..im willing to spend a pretty good amount

edit.... and i own a fairly good microphone that plugs into my amp i use for my guitar...is there some kind of thing that plugs into my computer that i could plug that mic into ? or a way to connect my amp to the computer?

 

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