You would be well advised to remove the CDRW from the primary channel and pop it on to the secondary. CD/DVD drives only transfer data at a max (from memory) bus speed of 15.5 Mbytes/second, which is the original IDE limit (even 52 times 150k/sec is less than 15.5Mb/sec)
Hard drives operate (depending on Motherboard) at 33, 66, 100 or 133 Mb/sec (and it could be higher although I seem to remember that parallel IDE peaked at 133).
Therefore, you are effectively limiting your primary channel to 15.5Mbyte/sec by attaching the CDRW.
Best to hang the hard drives off the primary channel and the optical(s) off the secondary.
Regards,
Shuttlebus