Don't be confused by the rated speeds you see emblazoned across USB 2.0 and FireWire product boxes. Despite USB 2.0's 80 Kbps speed advantage over FireWire, testing showed that the additional overhead of USB 2.0 made it slower than FireWire.
For high-bandwidth devices such as external hard drives, the difference was as high as 70 percent. On a positive note, we noticed that the CPU usage of each interface was similar on our Pentium 4 1.3-GHz test system. During a 1.54GB data transfer from our system's internal hard drive to an external drive, USB 2.0 averaged 40 percent CPU usage compared to 37 percent for FireWire.
If you need a high-speed interface, first consider what it is you are trying to do. If your only concern is getting digital video from your camcorder into your PC, then FireWire is the solution. If you have purchased an external CD burner that is "USB 2.0 ready" but records at a painfully slow 4x on your old USB 1.1 connection, then a USB 2.0 upgrade would be a good way to get maximum performance out of something you already own.
Despite the speed advantage USB 2.0 offers over the old v1.1 standard, FireWire remains the performance king of plug-and-play connections. USB 2.0 will be integrated into most new computers, but that's just a case of market dominance. FireWire will continue to be the connection of choice for digital video cameras, but digital still cameras will likely to move on to USB 2.0.
Another note consider if you are going to use an external HDD, that currently no manufacturer provides for booting to or accessing a USB drive from dos(don't know about firewire).
However you may find a usable USB DOS driver here:
http://www.addonics.com/support/download/usb/USBboot.zip and/or here:
http://www.freedos.org/freedos/news/newsitem/149.html
hope this helps