Here is the deal - people squabble about which is faster, usb or firewire. Let me just say that in actual real life use, firewire can be faster for audio than usb, but only if the firewire hardware on the motherboard is built properly.
One of the few reasons why Mac's were actually better for audio was that they had firewire ports with the proper Texas Instruments chips on the controller.
A lot of firewire ports don't actually have the right chipset to quickly move audio. Apple dropped the TI chipset for a while, then started to receive complaints from audio pros, then went back, but I recently heard some rumor that they were dropping the more expensive TI chipset again. I don't know.
But bottom line, you should research which chips were used for your firewire port if you wanna go with firewire. You generally can figure this out. I've seen pc/windoz machines with the TI chipset, but most don't have it, as the manufacturers only care enough to put a firewire port on the machine so they can get the sale, and could fucking care less if it actually works for its intended purpose.
With that said, really you can use either usb or firewire. You may have higher latency than you might like, but you can live with that to a certain extent.
Along with the specs of the audio interface, you should research into the quality of the drivers. This is of paramount importance. You can buy a big expensive excellent sounding box, that occasionally locks up, or doesn't really work with your os.
In regards to the driver, I strongly recommend an audio interface with a multi-client driver. This allows a whole bunch of audio sources to access the audio interface. This is extremely powerful, and for me now, a necessity. If you think I'm bollox on this one, take my word now, thank me later.
Head over to
http://www.gearsluts.com and research this question, you will find some pretty good detailed information from some down right knowledgeable people.
Also remember, that depending on the age of the laptop, you can also use pc card, or pcie interfaces. These are usually faster, less error prone than usb or firewire interfaces.
I love, and I mean love, emu's 1616m, it does everything I've mentioned. It sounds great and works perfectly (other than that sleep thing, that could be my fault).
And finally, don't buy anything from m-audio. Even if they try to sell it to you at the music store.
