At least this firewire interface has worked OK for me (so far so good ).

I bought a:

SYBA PCI to Firewire 1394a 3+1 ports controller card Model SD-NEC-4F

http://www.syba.com/us/en/product/43/01/11/3/

from newegg for $14.29 (including s&h)

// __
knoppix@0[knoppix]$ su
root@0[knoppix]# modprobe ohci1394
root@0[knoppix]# modprobe raw1394
root@0[knoppix]# gscanbus

* X window opened and when I clicked on S400 Linux - ohci1394 I got some prop info

// __
root@0[knoppix]# ls -l /dev/sda*
brw-rw---- 1 root disk 8, 0 Apr 14 2001 /dev/sda
. . .
brw-rw---- 1 root disk 8, 15 Apr 14 2001 /dev/sda15
root@0[knoppix]# mkdir /mnt/sda
root@0[knoppix]# mount /dev/sda /mnt/sda
root@0[knoppix]# cd /mnt/sda
root@0[sda]# ls -l
total 28
drwxr-xr-x 30 root root 4096 Sep 26 06:22 __ext
drwxr-xr-x 2 root root 4096 Sep 26 06:22 findpart
drwxr-xr-x 39 root root 12288 Sep 6 10:31 gates
drwxr-xr-x 3 root root 4096 Oct 12 08:58 iso
drwxr-xr-x 2 root root 4096 Oct 12 00:10 knoppix
root@0[sda]#

// __ then for testing I went to the drive and created, edited and deleted files without any problems

// __
root@0[/]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/root 2.5M 15K 2.4M 1% /
/ramdisk 1.6G 11M 1.6G 1% /ramdisk

/UNIONFS 8.4G 6.9G 1.6G 82% /UNIONFS
/dev/hdc 3.2G 3.2G 0 100% /cdrom
/dev/cloop 5.1G 5.1G 0 100% /KNOPPIX
/dev/cloop2 1.8G 1.8G 0 100% /KNOPPIX2
/UNIONFS/dev/sda 75G 56G 20G 75% /mnt/sda

// __
root@0[/]# df -i
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/root 8192 53 8139 1% /
/ramdisk 223837 758 223079 1% /ramdisk
/UNIONFS 223837 758 223079 1% /UNIONFS
/dev/hdc 0 0 0 - /cdrom
/dev/cloop 0 0 0 - /KNOPPIX
/dev/cloop2 0 0 0 - /KNOPPIX2
/UNIONFS/dev/sda 0 0 0 - /mnt/sda

// __ what has been mounted (notice the FAT32 vfat external harddrive /mnt/sda type vfat (rw))
root@0[/]# mount
/dev/root on / type ext2 (rw)
/ramdisk on /ramdisk type tmpfs (rw,size=1645636k)
/UNIONFS on /UNIONFS type unionfs (rw,dirs=/ramdisk=rw:/KNOPPIX=ro:/KNOPPIX2=ro,delete=whiteout)
/dev/hdc on /cdrom type iso9660 (ro)
/dev/cloop on /KNOPPIX type iso9660 (ro)
/dev/cloop2 on /KNOPPIX2 type iso9660 (ro)
/UNIONFS/dev/pts on /UNIONFS/dev/pts type devpts (rw)
/proc/bus/usb on /proc/bus/usb type usbfs (rw,devmode=0666) automount(pid2031) on /mnt/auto type autofs (rw,fd=4,pgrp=2031,minproto=2,maxproto=4)
/UNIONFS/dev/sda on /mnt/sda type vfat (rw)
root@0[/]#

// __ unmounting the firewire device
root@0[sda]# cd ..
root@0[mnt]# cd ..
root@0[/]# umount /mnt/sda
root@0[/]# cd /mnt/sda
root@0[sda]# ls -l
total 0
// __