Connect a set of speakers with a headphone jack to the speaker output from the motherboard or sound card. Plug a set of headphones into the headphone jack on the speakers. Plug your mic into a Digital Audio Recorder, something like...
Recorders with built-in microphones can be a good all-in-one solution for recording yourself. The ZoomH1nandH2nhave decent microphones and can even record directly to MP3 if you think you can do it in one-take, both for under $200. There also similar models from other brands listed below...