Play your CD through an equalizer and re-burn the music to a new disk. Every sound in a recording sits at a specific frequency range in the audio spectrum, including the human voice. Trimming frequencies at 120 Hz, 200-240 Hz, 5 kHz and 7.5-10 kHz can eliminate background talking. However, you risk thinning out the vocals that were intentionally recorded. This is the most recommended technique if the unwanted conversation is subtle, but trying to EQ out a louder voice runs the risk of ruining the music's overall sound quality.
Distort your recording using a distortion pedal or plug-in from your audio software. This is a bit of a drastic measure, but can cover up an unwanted noise if you need it to. What makes this so drastic is that the distortion effect will apply itself to the entire recording, making everything so noisy that you won't actually be able to distinguish background talking. If you can get away with a "grungy" or "industrial" sounding cut of your song then go for it, otherwise this technique may not be for you.
Re-record the track that had the background talking in it. This is the only sure-fire way to eliminate noises that you don't want.. It doesn't warrant any sort of EQ trickery and most importantly won't wreck your song. It might be frustrating to have to go back and do that work, especially if the track you are redoing is a saxophone solo or something of similar difficulty. When all is said and done, though, you will have accomplished your goal without compromising the quality of the work.