Visit the Hardware Zone for a look at Behringer’s Podcaststudio.  It consists of an analog mixer that supports XLR and RCA connections, a Firewire audio interface for your PC, a studio condenser microphone and a pair of high-quality headphones.  This will give you far better quality than a homebrew solution, unless you happen to have a background in sound engineering.
“No other podcast packages are as complete as Behringer’s Podcaststudio. If you are a musician and a podcast enthusiast, this package is the solution for you.”

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Audio Corner