For multi-person conversations in real time try to give everyone
their own mic, their own channel, and expect to clean up afterwards.
The sound level via a USB connection can be low, impacting the quality
so if you have a firewire connection, use Firewire microphones instead
Neumann - the best mics available today, they save a lot of
time cleaning up audio.
Zoom H2 Digital Recorder - can be preset to record .wav and
.mp3 formats and also serves as a fine USB microphone. Comes with
a windscreen, mic stand adapter and cables. Also doubles as music
recorder - records in 4-track surround sound, with guitar tuner
and metronome - around $150.
You will also need a microphone screen to reduce sibilant sounds
[words with 's' and 'ch'] and plosive sounds [words with hard 'p'
and 'b' sounds]. You can make
one yourself for less than $10. These sounds can also be reduced
by SMILING to stretch the mouth while speaking and using a boom
stand with the mic facing downward. You can test the effectiveness
by recording the following two statements:
"A steel seal searches childish snakes for chewy chocolates"
"Boldly balancing pickles on punks in poodleskirts"