There are 2 possible ways you can go about this: one is to get individual parts such as a mixer (some models have preamps already) and a separate interface for flexibility; or you could get a mixer with a built in audio interface such as the mackie (or phonic) usb or firewire mixers.
Each has his advantages and disadvantages. The former means having a lot of individual gear to power up along with the necessary cable interconnects, while the latter means only one piece of gear to lug around. The downside of the combined mixer/interface route is that if it goes down, then your recording setup is compromised.
What you should think about is how many inputs you will require then decide on the interface. Some audio interfaces now include mic preamps so that means one less piece of gear. Of course, the more inputs you require, the more expensive the interface.
One more thing... make sure your laptop (or pc) is up to the job. The requirements for audio are not as stringent for video, but you still need a relatively powerful laptop and sufficient RAM and HD space. Another thing is the amount of usb or firewire ports in the laptop. USB2 is the better choice for most interfaces, but some laptops don't have usb2 ports, so choose wisely. Also, don't forget that the DAW software determines what kind of computer you will use. No point in getting a windows based laptop if you intend to run Logic or Digital Performer on it.