I feel your pain.
I have a dual boot system. Windows XP (mainly to run Quicken and BF 1942). I have been using linux/freebsd/solaris for 15+ years and can do just about anything with these systems. I am very baffled as to the lack of any real FAQ that work with linux and Promise.
Reason for going with a raid card:
First reason was I wanted a solution that would work with windows AND linux. Since windows raiding leaves alot to be desired I went with Promise (I also have a adaptec 1200a which is a highpoint chip)
Second I was tired of BF 1942 taking 2 min to load everytime I joined a server. I have 4 120G drives so I threw them in the system and started over with both OS builds. Debian and Windows XP. I decided to go with XP first has it is brain dead easy. I popped in the floppy that came with my Promise Fasttrak 2000 and set it up as raid 0 + 1 with 128k stripe. After windows got configured I loaded the BF 1942 and saw an immediate gain in joining. Also the disk to disk copy and other disk related I/O was amazing. With a lack of any real benchmarking software I am unable to say how much faster it is but OMG it was fast.
Now to Debian or Knoppix or hell I would even throw RH back on if I thought it would work. I have spent over a week trying to get a 2.4 or a 2.6 kernel to work correctly.
Since I have a dual boot I let the windows install take about 50 percent so that left me with installing debian on the other half.
Knoppix does not work with promise so that left me with a going through the debian lists to figure out if someone else had done it. Amazing I followed the examples to the letter and ran into several issues of which in the end none of them worked. (Typical problem is that the distro install did not see any of the raided partitions but would see the disks....)
Note that saying that you can use the raid that comes with linux is NOT an answer. With windows it only sees the raided partition. With linux all I see is the individual disk drives. (Which on a 4 disk raid 1/0 is unusable).
So the net end of it is that linux again fails to do any one thing great outside running apache. As a dual boot desktop or a workstation it is has failed after years of people coding for free. It is still my server of choice and I continue to run it on a laptop for work (Eclipse/vi/unix) but as for home use with a simple raid card that has been around for 10 years it has come up short.
Just a quick frustrating note: What is the point of having a driver for a promise card in the 2.4 or 2.6 kernel if you can't use the card ? On a stand alone linux workstation I would simply chuck the promise card in favor of the built in raid ? For a dual boot that shares 2 or more drives accessing the /dev/hdX and using raid is pointless as you would write over the partitions used by the other OS. Am I missing something here ? Why does the device not show up as a /dev/something as what the promise card carved up ?
Also note that another answer I saw which is also not a valid answer is to use the drivers for RH that came with the card. I could however using RH 7.2 is not a real OS since it is outdated and also no longer supported.
Anyhow I will prob separate 2 of the drive back to the MB ide controller and run debian with md/raid. I will leave 2 of the drives on the promise and run XP.