What sound card should I get? USB or Firewire?
A sound card is also known as an "Audio Interface".
There are 3 basic types of sound cards:
1) PCI
2) Firewire
3) USBPCI connects right behind your pc. It's a bit difficult to access it, but it has little latency.
USB audio interface is easy to access it but has more latency.
Firewire audio interface is easy to access it and has little latency as PCI.
So you recommend firewire, but what's the difference between USB and Firewire?
USB promises you more speed, but it doesn't uses this speed at maximum.
FIREWIRE promises you less speed, but always uses this speed at maximum.
To help you understand:
ISP No1 (Internet Service Provider) promises you up to 24mpbs/sec speed. But it usually is at 15mpbs/sec.
ISP No2 promises you 20mpbs/sec (less than ISP No1) but always at 20mpbs no less and... stable.
Let's say that ISP No1 is USB and ISP No2 is Firewire. Which would you prefer?...
... Right. You got the point