I havent worked with those particular devices much (when I do recording to a PC, its to a desktop), but know people who have. they work great, depending on the gear of course. like anything else, some stuff is junk, some is good at a good price, some is way overpriced but works really well (read that as anything labeled "digi")
these things work best on USB 2.0, with the much higher bandwidth it provides. even better is firewire- lots of great gear using that interface. if you want more info on that, ask.
a quick glance turned up this
, which is a good box at a good price. has proffesional I/O, midi, etc.
there are also boxes available using rca I/O if you need that. just click the usb page of the recording section to see it all.
no real worries about the machine being in the room, unless you have the bass turned up so loud it could vibrate the laptop off the table!
volumes down, keep instruments separated if possible (to avoid bleed on tracks), etc. listen to the results on many different speakers, to get an idea of how it really sounds, not just how it sounds in one room (which may have strange effects on the balance of the sound)
a prime example, a room can have a standing wave problem for the bass, so you turn it up so it sounds right in there. listen to the tracks on another stereo, and the bass is way too heavy. hope that gives you an idea of what I mean.