Ok these are the drives which I have in my PC:
Pioneer DVD-RW DVR-104
Plextor CDRW 40/12/40A
Toshiba DVD-ROM SD-M1302
1x IBM 40GB Hard Drive
2x Western Digital 120GBS SE (striped)
I had terrible problems with communication errors in NERO when burning with the DVR-104 I had to use PIO mode which hammered my CPU, and it didn't do CD2CD on the fly too well. What I tried was to put the DVR-104 as slave on the primary channel in DMA mode!! and the Plex as Master and Tosh as slave on the Secondary Channel(Both DMA), I am now successfully simulating without any communication problems!! on top of that I did a test burn with the Plex and Tosh while burning with the DVr-104 at the SAME time and all is well!!
Hope that info helps someone!