I am running Promise FastTrak TX2000 with Slackware 9.1 without any problems. Had to do the following though to get it to work on fresh install:
1. Boot up with ataraid.i kernel as follows:
boot: ataraid.i ide0=0x1f0,0x3f6,14 ide1=0x170,0x376,15 ide2=0 ide3=0 ide4=0 ide5=0 ide6=0 ide7=0
2. Once you're booted up and slackware is installed, you must put those same parameters in your lilo.conf file in the "append" field.
3. your drives will now be called something like this: /dev/ataraid/d0p1
I've partitioned my drive as follows for RAID 0:
First partition: /boot (/dev/ataraid/d0p1)
Second partition: swap
Third partition: / (/dev/ataraid/d0p3)
After that, you should be fine.