In Home Recording Studio Equipment I said you can buy either a preamp + soundcard, or an external audio interface. I really think it all depends on you and your budget. If you have a laptop or if you know you'll be moving your stuff a lot, an Audio Interface is what you need. If you are on a tight budget and have an old PC you can buy an internal soundcard + external preamp. It would be cheaper, but you will loose some sound quality there. In both cases, I would go for a good audio interface.
One of the best audio interface for a Home Studio Project is M-Audio ProFire 610 Firewire Audio Interface.
Features (via Amazon Shop)
6 x 10 simultaneous analog/digital I/O ideal for mobile and studio recording
2 preamps with award-winning Octane technology.pristine sound and exceptional headroom
premium digital converters.high-definition, 24-bit/192kHz audio throughout signal path
flexible onboard DSP mixer.create multiple unique cue mixes
user-assignable master volume knob.customize your setup
6 x 10 Simultaneous analog/digital I/O ideal for mobile and studio recording.
If you'll use this audio interface and a good microphone, you'll be able to get recordings comparable to big budget recording studios. ProFire 610 works great with Windows 7 64bits while other soundcards in this price range struggles with driver problems (like EMU).
As an alternative, you can buy a mixer that features Phantom Power, and connect that to your internal soundcard through line-in.