"My first preference is a usb or firewire powered external device with at least four outputs, two inputs and latency lower than 10ms. Because I've my eye on the M-Audio firewire 410 (which is not out yet), I'm especially interested in people's experiences with M-Audio drivers in Live (lowest usable latency and at what cpu usage audio begins to break when using the lowest latency). Because I have never used USB or Firewire devices, I also need to know about the quality to expect."
Even though usb 2.0 is faster on paper than firewire (480 MBps vs. 400 MBps) by EVERY account I've heard, the experts say don't even try to do high quality, low latency audio on usb. If you have firewire or pmc-cia or pci capablities, go ahead and forget about usb audio.
"1. All USB devices from M-Audio, ESI, Edirol and Emagic."
"2. All Firewire devices from MOTU and eventually M-Audio and ESI."
I recently went trough the same process as you on a smoking new toshiba satelite 2430, P4 2.4 desktop processor (better than mobile as mobile processors are designed to optimize battery power no audio), 1 gig RAM, external 120 gig 7,200 8 MB cache FW drive, RME multiface with pcm cia cardbus. My research into firewire options on pc led me to decide not to use firewire for a few reasons: the firewire devices availible: MOTU, FIrestation...are, by many account of users online, a bit of a pain to get solid predictible results on a pc. IE setup is sometimes a nightmare, or the firewire chips manufacturer used in your computer might not be compatible...lots of reports of problems out there with pcs. Not only that, but definitely on the firestation (and somewhat on the MOTU), there are some latency issues because the devices use some of your computers processing power--thus creating more latency. In the end, pci is the fastest way to get audio in on a desktop, and the pcm cia cardbus is the best on a laptop--this is simply based on the data tranfer rates possible with these connections vs. usb, firewire... A soundcard like the RME Mulitface--which i couldn't be happier with--acutally does all the processing itself, creating a "zero CPU load" situation--i.e the RME doesn't tax your computer to do it's thang. I just recorded 8 tracks live with 2 ms latency into live and 4 ms out at 24 bit 44.1--no glitches, just quality audio. If you are getting/using live to preform live, the lower the latency the better, can't go much lower than 2/4 ms!
That's my experience and 2 cents for you..