I don't know squat about Nero but I have a similar drive (HP 9110i) and have no problems burning at 8x. That's the only speed that I burn at with this unit or my Plextor 8432A.
Have you ever been able to burn at 8x with Nero? I would try some other s/w and experiment with different media brands. Although both my HP and Plextor will burn at 8x using just about ANY brand of media: no name, GQ or Great Quality (CMC Magnetics), Fuji Film, Taiyo Yuden, Verbatim, Maxell, Sony, TDK, Memorex, and Kodak. Tried em all, no problemos!
The BEST CD mastering s/w overall, in my opinion, is WinOnCD Power Edition. I've had no problem at all using it, worth every penny. Has all of the user friendliness of Adapcrap Easy CD Creator but is much more stable and robust.
These are the apps that I use and have virtually no problems with for on-the-fly burns at 8x: CeQuadrat (now a part of Adaptec) WinOnCD v3.7 Power Edition, Adaptec Easy CD Creator Standard v3.5c and Deluxe v4.02d, Padus Diskjuggler v3.0-750, and Goldenhawk CDRWin v3.8c. Also had good luck with Feurio although it is only good for making audio CD's which WinOnCD does a much better/easier job of in my opinion.
In each of my systems, I have DMA mode ENABLED in Win98SE (a MUST for some CDRW drives to burn at 8x, Plextor recommends this for example), each CDRW drive is configured on the Secondary IDE channel as MASTER, in each system I have a Kenwood UCR-421 72x CDROM reader configured on the Secondary IDE channel as SLAVE. You should only hang HD's on the Primary channel. This is the only configuration that would work for me and I tried every combo possible...
Heiny