That settup is fine as long as you don't plan on doing CD to CD coppies. If you do plan on doing such copies, remember than IDE can only access one drive per channel at a time, so it would be better to have your DVD on the primary slave position.
It seems you also like to pay 10x as much. I used to like SCSI, but the performance difference is now negligible and I can implement IDE RAID that will stomp a single SCSI drive and cost me less money. I may even have some left over to buy something else.
In addition, with ACPI, all PCI devices use the same IRQ, so no benefit there....
Back on topic, I would usually recommend placing the CDRW as master on the secondary controller, but this changes with having two UDMA66/100/133 drives and a UDMA66 DVD (like the Pioneer 116 or 106s). The CDRW will actually slow down the other devices as master. CD to CD copying will not be too badly impacted with the DVD as master and the CDRW as slave if you have enabled UDMA for the DVD. I have set-up my two HDs, DVD, and CDRW as shown above and have no difficulty with CD to CD (full burn at 12X no problem). I also have burns streaming of HD #2 and this works great as well.