Basically, in order to use a laptop (or a desktop) for audio recording of even mediocre quality, you have to either bypass the soundcard or replace it. It is almost always simpler to bypass it, and the standard way is USB or firewire. Usually on a laptop, you use USB. While there is such a thing as a USB mic, it is way more versatile to use a converter to change the mic signal to digital, which means it needs to have a mic preamp and an A-D convertor. A USB mic has these built in, usually wicked cheap ones. There are some expensive exceptions. A separate interface is more useful, because you can plug any mic (s)you want into it. There are simple (and very portable) ways to do this, such as:
http://www.8thstreet.com/product.asp?ProductCode=42882&Category=Audio_Interfaces
However, it's handy to have a headphone jack, 2 or more channels, and better preamps, so for anything more than a simple podcast, I would recommend a USB based interface, such as:
http://www.8thstreet.com/product.asp?ProductCode=40819&Category=Audio_Interfaces
or
http://www.8thstreet.com/product.asp?ProductCode=60669&Category=Audio_Interfaces
You'll need some software for audio processing. Audacity is free, and lots of people like Reaper, which is about $50. A good set of headphones will be very useful. Good Luck-Richie