Would a "USB sound card device" be the 'M-Audio USB MobilePre' that so
many of the respondants are suggesting?

Even something as simple as a Creative Soundblaster USB would work.

But to back up a bit, is this a desktop or laptop machine and does it
already HAVE a soundcard installed in it? If there's already a MIC input
jack then just use whatever mic best suits the way you'd be recording. If
it's a desktop machine then put in a PCI card. If it's a laptop them you'd
obviously have to use either a PCMCIA card or USB. USB probably being
easier.

As to whose USB device to get it largely depends on the price compared
against the quality needed. For voice recording it may well be overkill to
get into some of the more expensive USB devices. They're great and offer
great quality but you may find your money better spent on the microphone
itself.

-Bill Kearney