I have an overview of setting up a laptop for looping at www.rekliner.com?PageID=15 PCMCIA is faster and less cpu-intensive, but the options are very limited...I can't find any cardbus interfaces that support 4 analog ins/outs. It's either stereo in/out or 8 million digital in/outs in a rack-unit like on hammerfall. You also have to deal with flimsy adaptors & cables. Firewire is a dependable standard, and I can get a consistant 64 sample latency with the M-audio Firewire 410 (3ms from guitar to amp). I have heard that other firewire interfaces are only as good as their drivers - and bad things about the Presonus firestation. But I firewire can't be dismissed as being in the same category as USB. USB is an entirely different and slower spec never meant for audio.... USB 2.0 has more bandwidth than firewire but from what I hear it is still slower to deliver the data in a time-critical fashion...it only gets cranking when you are transferring files and such. Per Boyson wrote: Do not go for USB audio or FireWire audio with PC. Go for a PCMCIA card. One that is loved by many laptop PC musicians is the Indigo Echo i/o. It gives you stereo in and stereo out with superb sound quality to a modest price.