Sorry to rain on your parade Bob, but unless the laptop has more than a single headphone socket, you are not going to get surround sound, only stereo. However some really new laptops do have decent sound, certainly not at the level of a dedicated interface, but good enough for MP3 playback.

Re latency, I already made that point clear in the post - read it.

USB interface is only really decent if using USB2, and even then can be subject to cracks pops and other noises due to the USB circuitry, not to mention ground loops if the laptop has an earth pin on the power supply. USB 1.1 is barely useable, but again acceptable if used in low-stress environments.

Most modern keyboards (apart from arrangers, and even then only the top models) have no audio interfacing of any quality afaic, apart from the odd XLR input. If I want to record mics I certainly would not be running them via noisy and lower grade pre-amps that are stuck into keyboards.