[HAL9000]

The CD-RW isn't going to slow down the hard drive to mode 4 unless you are using it. Like I said, there are going to be a number of ways of doing it, each with their pro's and cons. My reasoning for doing it this way (and it still may not have any advantage over another) is;

1) The hard drives are on separate channels for max performance when accessing both drives.

2) The CD and CD-RW are separated for max performance for on the fly CD copying (although copying to the hard drive first is often a better idea, especially with more difficult to copy, copyright protected CD's). Hard drive to CD-RW performance isn't really a concern as even with the master/slave of the hard drive/CD-RW, the hard drive is more than fast enough to keep up with the CD-RW.

3) Becomes a pro/con situation. If your programs that require the CD to run are on your primary hard drive, the CD is now on a separate channel from the hard drive and you will get better performance, pro. If your programs are on the secondary hard drive slaved to the CD, you will have reduced performance, con. You could always use the CD-RW as the CD drive for your programs on the secondary drive and regain the performance loss, pro. If you did that, you would have to keep track of which program uses which CD drive and put more wear and tear on your expensive CD-RW instead of your cheap CD-Rom, con.

Now if we looked at the first scenario of the hard drives mastered/slaved and the same with the CD drives;

1) The hard drives are separated from the CD drives for max performance between CD/CD-RW and the hard drives, pro. When both hard drives need to be accessed, only one can be accessed at a time reducing performance, con.

2) No need to ever use the CD-RW for anything other than CD writing, so less wear and tear on that drive, pro. For best results, CD to CD recording should now be copied to the hard drive first for best results and least chance of a buffer underrun (although should not be a problem with burn proof or similar technology drives) con.

Each has it's upside and downside and in this situation, I don't think there is any cut and dry situation of which is better than the other. Personally, what I have done on my own and on customers machines is to install a Promise Ultra66/100 card (you can get them dirt cheap now) and put EVERYTHING on a separate channel.