* If I purchase a mixer, then I go from mic to mixer, and then out from mixer (probably digital) into my existing sound card.
* If I purchase a dedicated "recording" sound card, then I can go mic to sound card.

Looking out at mixers and at "studio" sound cards, it occurs to me I could spend roughly an equal amount of money on either. I am leaning towards the sound card, but I'm a little concerned about having two sound cards (the other for gaming, which I do occasionally). Since I'm doing the recording myself, I don't expect to need more than one mic at a time. The mic, at least in the beginning, will be a Shure SM57 or Beta. The recording will be of guitar amp, acoustic guitar, and vocal. All other instruments I'm doing electronically on the PC.

Any advice or experience you guys can give me?

Have you considered a pre-amp? I mean for guitar and microphone?

You need a microphone preamp. There may be microphones somewhere, such as those in some telephones, that don't require much in the way of a preamp, but none that would be a reasonable consideration for recording.

Mixers frequently contain microphone preamps but not necessarily. Although they can be very useful in more complex setups, there is no absolute need for a mixer between a microphone and the soundcard.

Some soundcards contain very good microphone preamps, but probably no PCI soundcards except those with a breakout box to house the preamp(s) and converters. Those built into soundcards such as Soundblasters are best left to dictation and internet chat rooms.

So, unless you don't intend to record music, or anything else where quality is important, only consider setups with a quality microphone preamp. Many firewire, and some USB, soundcards contain good preamps. Many mixers contain good preamps. Many stand-alone microphone preamps are available.

I'd recommend a small Behringer mixer into something like a M-Audio 2496.

- Do not get a "digital mixer". Do not get a mixer at all unless you need to mix things. Get an analogue preamp if you decide not to get a soundcard with preamps.
- Try the 0404 USB from E-MU. It comes with mic preamps and phantom power.

I am familiar with phantom power. Is this not the same thing as preamp for mic?

Phantom power supplies power to microphones that require it (some condensers, electrets, etc). It is not a preamp.